Impact of early multidisciplinary team interventions on dietary management behavior in breast cancer patients: a pilot randomized controlled trial

Abstract

Background

Chemotherapy side effects can easily contribute to malnutrition and disrupt the normal diet of breast cancer patients. Offering early multidisciplinary team interventions during chemotherapy can establish a solid groundwork for dietary management and enhance the quality of life throughout the survival period. This study aims to assess the impact of early multidisciplinary team interventions on dietary management behavior, self-care self-efficacy, quality of life, and body mass index in breast cancer patients undergoing chemotherapy.

Methods

A prospective, two-arm, single-blind, single-center randomized controlled trial was conducted between November 2023 and July 2024 from a tertiary-level general hospital in Shaanxi, China. A total of 88 participants who were either preparing for or undergoing early or middle stage chemotherapy were enrolled for this intervention. The intervention group received diet-related early multidisciplinary team interventions, in addition to the usual dietary education. The control group only received the usual dietary education. The intervention program included 8 themes, which were covered each week. The data on dietary management behavior, self-care self-efficacy, quality of life, and body mass index were measured at baseline (T0), immediately after the intervention (T1), 1 month after (T2), and 3 months after (T3) the intervention.

Results

Seventy-nine participants, divided into an intervention group of 40 and a control group of 39, completed all the measures. There were statistically significant intergroup effects between the two groups and time effects on dietary management behavior, self-care self-efficacy, and quality of life. Additionally, there was an interaction effect (P < 0.05). However, there was no statistically significant intergroup effect on body mass index before and after the intervention (P > 0.05).

Conclusion

The early multidisciplinary team interventions are an effective method for improving dietary management behavior and confidence among breast cancer patients undergoing chemotherapy. Nurses should be attentive to the dietary issues faced by female patients during chemotherapy and should work to train and organize a multidisciplinary team to provide this intervention. This may lay a theoretical and capable foundation for managing a healthy lifestyle for future survival period.

Trial registration

This intervention was registered with the Chinese Clinical Trials Registry (ChiCTR2300076503, October 10, 2023).

Background

According to the latest global cancer epidemiological data released by the World Health Organization [1], there were 2.3 million new cases of breast cancer (BC) in 2020, surpassing lung cancer as the most commonly diagnosed cancer. It is projected that by 2040, due to population growth and aging, the number of new BC cases worldwide may increase to at least 3 million per year, further exacerbating the burden of the disease [2]. Despite the high incidence of BC, several studies [3, 4] have confirmed that the 5-year relative survival rate of BC patients is also high in China. Additionally, the proportion of BC survivors is steadily increasing, largely due to the availability of various treatments and advancements in their effectiveness.

Chemotherapy is widely recognized as one of the most common and effective treatments worldwide. However, it unavoidably damages normal cells and produces a range of side effects. Several studies [5, 6] have demonstrated that female patients undergoing chemotherapy experience the most severe and frequent adverse reactions, particularly gastrointestinal symptoms. These symptoms interfere with normal dietary intake, leading to unhealthy eating habits and subsequent abnormal fluctuations in body weight, body composition, muscle strength loss, and psychological well-being [7]. As young BC patients have a higher incidence rate and survival rate, they have a solid foundation for managing their own health. Therefore, it is important to focus on promoting a healthy lifestyle for these patients.

Diet is crucial for BC patients undergoing chemotherapy, as it directly affects their treatment outcomes and subsequent recovery [8]. Some studies [9, 10] have advocated for early dietary and nutritional interventions for cancer patients, rather than waiting until the treatment is complete, to mitigate the risk of malnutrition. However, there is limited evidence on the effectiveness among BC patients during chemotherapy. Additionally, most of the existing interventions are conducted by doctors, dietitians, or nurses alone, despite the fact that diet is a complex behavior influenced by various factors such as physiology, psychology, culture, environment, and society [11]. Therefore, it is essential to involve multidisciplinary team who can leverage their expertise to provide tailored dietary self-management interventions.

As there are no commonly recognized definitions of multidisciplinary team interventions, a similar definition in a previous literature [12] among the elderly residents can be framed from multidisciplinary members, which is “multidisciplinary approach, integrating a team of healthcare professionals from different disciplines and specialties, aimed at reaching a combined decision and offer assistance”. Besides, another study [13] about multidisciplinary team intervention defined it from the perspective of contents, it includes multiple health improving measures (such as physical activity, sleep and stress management) to significantly enhance disease activity in patients with rheumatoid arthritis. Therefore, there are different subsections about the intended meaning of multidisciplinary team interventions. In terms of BC patients undergoing chemotherapy, there is a dearth of multidisciplinary team interventions on female diets, with the majority of participants being BC survivors. One study [14] conducted multidisciplinary team interventions comprising oncologists, nurses, and acupuncturists for BC survivors, incorporating massage, exercise, diet, and stress management. While it showed improvements in chemotherapy-induced fatigue, specific information on diet was lacking. Moreover, previous studies [15, 16] primarily measured outcomes using laboratory indicators, body weight and fat percentage, food intake, and incidence of adverse reactions, neglecting subjective and comprehensive indicators reported by patients. In China, with its deep-rooted food culture, traditional Chinese medicine (TCM) and food therapy play a significant role in the beliefs of BC patients. These aspects should also be considered in dietary management interventions. Combining the characteristics of BC patients during chemotherapy with above-mentioned subsection about intended meaning of multidisciplinary team interventions, it should adopt a holistic approach by different healthcare professional members. According to their expertise, they provide BC females with comprehensive and specific intervention contents encompassing physiological, psychological, social and cultural elements to effectively facilitate dietary management behavior in our study. The specific details of the intervention protocol have been previously reported [17].

Given the potential benefits of early multidisciplinary team interventions in dietary management during chemotherapy for BC patients, we have designed targeted and scientific intervention programs that integrate theory and practice. These programs are developed based on the guidance of health behavior change theory and the characteristics of Chinese food culture. The objective of this study is to initially evaluate the short-term effectiveness (within 3 months after the intervention) of early intervention during chemotherapy for BC patients provided by multidisciplinary team. We aim to assess its impact on dietary management behavior, self-care self-efficacy, quality of life, and Body Mass Index (BMI). We hypothesize that the intervention program will improve females'dietary management behavior, enhance self-care self-efficacy, and improve quality of life, while maintaining BMI within the normal range.

Methods

Study design

This was an 8-week prospective, two-arm, single-blinded, and single-center randomized controlled trial (RCT) conducted between November 2023 and July 2024 at two oncology departments in a tertiary-level general hospital in Shaanxi, China. The study was registered on the Chinese Clinical Trials Registry (ChiCTR2300076503, October 10, 2023). The report followed the guidelines of the Consolidated Standards of Reporting Trials (CONSORT) statement [18] (Supplementary materials 1).

During the design stage, we utilized the'Integrated Theory of Health Behavior Change (ITHBC)' [19] as our guiding framework. This theory posits that knowledge and belief, self-regulation, and social support are the three primary factors that promote health behavior change. Together, they lead to various proximal outcomes (such as self-management behaviors) and distal outcomes (such as overall health status). In our study, we focused on improving dietary management behavior in BC patients undergoing chemotherapy as a health behavior change. As a result, we emphasized elements such as dietary information education, psychological adjustment, and social support, which should be incorporated into the intervention contents. Furthermore, based on the outcomes suggested by the ITHBC, we selected dietary management behavior and quality of life as outcome indicators for this intervention.

Participants

It was difficult to blind the implementers (multidisciplinary team members) and recipients (patients) of the intervention, so only the statisticians responsible for statistical analysis did not know the grouping assignment. Participants were recruited through active outreach and the dissemination of recruitment information by two of our research members. The active outreach method involved health professionals recommending patients who met the potential inclusion criteria. Additionally, we displayed posters in the waiting room of the oncology department and sent advertising messages through WeChat groups and email. Each participant was assigned a unique identifier based on their enrollment order. Using the random number table method, the patients were then randomly assigned to either the control group or the intervention group in a 1:1 ratio. Starting with the numbers in the fifth row and sixth column of the random number table, 88 different numbers were selected from left to right, and then sorted from smallest to largest, with the smaller 44 numbers assigned to the control group and the rest assigned to the intervention group. The random sequence was unknown to the remaining research members except the statistician.

The inclusion criteria [17] for participants were as follows: (1) adult patients (≥ 18 years old) with a pathological diagnosis of BC, who are informed about their disease and chemotherapy regimen; (2) preparing for or currently undergoing chemotherapy (including adjuvant and neoadjuvant chemotherapy); (3) have not yet initiated or are in the early to middle stages of chemotherapy (for patients scheduled for 4 cycles of chemotherapy who have not yet had their first or second admission; for those scheduled for 6 cycles who have not yet had their first, second, third, or fourth admission; and for those scheduled for 8 cycles who have not yet had their first, second, third, fourth, fifth, or sixth admission); (4) able to feed themselves orally without assistance; (5) no requirement for additional enteral or parenteral nutrition support as determined by health professionals; (6) able to speak and understand Chinese, aware of this research, and agree to participate voluntarily; and (7) in good physical and mental condition to persist with the intervention.

The exclusion criteria [17] were: (1) terminal cancer stage with a predicted survival of less than 6 months; (2) planning to become pregnant, currently pregnant, or becoming pregnant within 6 months post-delivery; (3) history of psychiatric illness, severe cognitive impairment, or severe visual, hearing, or language impairment; (4) poor nutritional status, pathological eating disorder, morbid obesity, etc.; and (5) participation in similar research or lack of family consent.

Sample size

In the sample size calculation for this intervention, we initially utilized the ANOVA and a priori power analysis model of G*power software. However, since there were few related references on multidisciplinary team interventions that provided detailed parameters for sample size calculation using the same methods, and the use of system default parameters was not rigorous, we decided to use the sample size formula for comparing two sample means after discussion. To minimize heterogeneity, we also considered preliminary experimental findings and conducted a literature search in Chinese. The standard deviation (s) of the difference in scores between the two groups after the intervention for three months was estimated to be approximately 7.0 [20]. The intergroup difference (δ) was 5.3, with a beta (β) of 0.10 and an alpha (α) of 0.05. Based on these calculations, the total sample size was determined to be 72, with 36 participants in each group. Taking into account a potential loss-to-follow-up rate of 20%, the final sample size for each group was adjusted to 44, resulting in a total of 88 BC patients.

Intervention

Early multidisciplinary team interventions

The patients in the intervention group received early multidisciplinary team interventions in addition to their usual care. Three weeks before the formal intervention, we invited and trained 4 oncologists, 4 clinical nurses, 1 dietitian, 1 TCM practitioner, and 1 psychologist to form the multidisciplinary team for BC patients. Face-to-face group training was conducted three times, once a week, for 2–3 h each session. The training covered various topics, such as coping with gastrointestinal reactions after chemotherapy, the relationship between hormone levels and diet in female BC patients, the selection of dietary nutrition supplements, stress and weight management, as well as the importance of the intervention, precautions, and specific roles and responsibilities within the multidisciplinary team. The intervention itself consisted of 8 themes, with sessions conducted once a week throughout the admission chemotherapy period (face to face) and intermission of home chemotherapy (online). The format of the intervention involved a combination of groups and individuals. The 8 weekly themes covered ‘adverse reaction management, dietary information and habit regulation, self-care self-efficacy training, treatment self-regulation training, dietary supplements and TCM use, seeking social support, and education on outcome expectations’. The content of the intervention was based on Chinese food culture, while also considering the key elements of ITHBC, covering knowledge and information, as well as psychological and social aspects. Moreover, we referred to the Dietary Guidelines for Chinese Residents, the National Comprehensive Cancer Network (NCCN) clinical practice guidelines for BC, and the World or American Nutrition Guidelines to determine the recommended daily types and quantities of different foods to be consumed during the intervention.

Control group: usual care

Patients in the control group received standard admission health education from the department. These included doctors asking about the patient's condition after admission and providing basic information about BC disease. In addition, nurses distributed paper-based health education manuals and guidelines about BC chemotherapy, which covered adverse reactions and coping strategies. The health professionals also discussed the relationship between chemotherapy and diet, explained how to regulate dietary habits, provided psychological management strategies, introduced TCM and food therapy, and recommended the necessity and methods of weight management. All of this was done through regular patient education meetings. During the admission chemotherapy period, health professionals used face-to-face communication, question-and-answer sessions, live demonstrations, and other forms to educate patients. For patients receiving intermittent home chemotherapy, assistance was provided through phone calls, WeChat, online meetings, emails, and other means as needed.

Data collection and outcomes

The aim of this study was to initially evaluate the short-term effectiveness of the intervention. To do this, two professionally trained research members collected patient data at three different time points: baseline (T0), immediately after the intervention (T1), and 1 month (T2) and 3 months (T3) after the intervention. At T0, paper questionnaires were handed out face to face to patients who were admitted to chemotherapy. These questionnaires were collected on the spot to ensure that there were no missing, wrong, or illegible responses. Other measurements were collected through an electronic questionnaire collection platform. Preliminary pilot test results indicated that the average filling time for the questionnaires was 10–20 min. Data less than 6 min or more than 30 min were excluded and participants were asked to refill the questionnaire. At each measurement point, the following outcome indicators were collected: demographic and clinical information, dietary management behavior, self-care self-efficacy, quality of life, and BMI.

Primary outcomes

Dietary management behavior

The patient-reported Dietary Self-management Behavior Questionnaire (DSMBQ) was used to measure dietary management behavior. The DSMBQ was developed and validated by our research team in 2024 [21]. It consists of 22 items organized into 4 dimensions:'adverse reaction coping'(4 items),'dietary information acquisition'(5 items),'dietary habit regulation'(8 items), and'nutritional supplements and dietary replacement'(5 items). Participants rated each item on a Likert scale ranging from'strongly disagree'(1 point) to'strongly agree'(5 points). Higher scores indicate better dietary management behavior. The total score of the questionnaire is calculated by summing the scores of all items. The average score for each dimension is calculated by summing the scores of the items within that dimension and dividing by the number of items. A higher score on the questionnaire indicates better dietary self-management behavior in BC patients during chemotherapy. The total cumulative variance contribution rate of the 4 dimensions and the 22-item questionnaire was found to be 62.67%. The split-half reliability coefficient was 0.833, and the test–retest reliability coefficient was 0.938. The Cronbach's α in this study was 0.908. In confirmatory factor analysis (CFA), with the exception of the Normed Fit Index (NFI) and Non-Normed Fit Index (NNFI), which were at 0.89 (close to 0.90), all other indicators met the statistical requirements, including χ2/df = 3.15, Goodness of Fit Index (GFI) = 0.89, Adjusted Goodness-of-Fit Index (AGFI) = 0.89, Comparative Fit Index (CFI) = 0.92, Root Mean Square Error of Approximation (RMSEA) = 0.048 [21].

Secondary outcomes

Self-care self-efficacy

Self-care self-efficacy was assessed using the Strategies Used by People to Promote Health (SUPPH) scale, developed by Lev et al. [22]. In 2011, a Chinese scholar translated and adapted the scale, which has since been widely used among Chinese cancer patients. The Chinese version of the scale consists of 28 items across three dimensions:'positive attitude'(15 items),'stress reduction'(10 items), and'decision making'(3 items). Participants rated their level of confidence using a Likert- 5 scale, ranging from'very little confidence'(1 point) to'very confident'(5 points). Scores on the scale can range from 28 to 140, with higher scores indicating greater confidence in managing one's own health. In this study, the Cronbach's α was found to be 0.98.

Quality of life

The quality of life was assessed using the Chinese version of the Functional Assessment of Cancer Therapy-Breast (FACT-B, version 4), which was introduced to China in 2002 [23]. This self-reported instrument is a widely used assessment tool and validated among BC patients worldwide [24]. It consists of 5 domains and 36 items, including domains for physiological well-being (PWB, 7 items), social/family well-being (SWB, 7 items), emotional well-being (EWB, 6 items), functional well-being (FWB, 7 items), and additional concerns (AC, 9 items). Participants rate the items on a 5-point Likert scale, ranging from'not at all'(0 points) to'very much'(4 points). Higher scores indicate a better quality of life. The Cronbach's α for this tool in this study was 0.94.

Other outcomes

Demographic and clinical information

A self-designed scale was employed to collect demographic and clinical information. The scale included detailed indicators such as demographic factors (age, BMI, marital status, number of children, educational level, per capita monthly household income, living conditions, work status, and menopausal status) as well as clinical information (time of diagnosis, unilateral or bilateral BC, cancer stage, and chemotherapy type).

BMI

Each patient was given an electronic weighing scale with the same make, model, and batch. The patients were instructed to perform the measurements in the morning after defecation and urination, while wearing only underwear. The weighing took place between 7–8 am, and the data was then uploaded to their dedicated App. The screenshots of each measurement were recorded and checked by two researchers. These measurements were then entered into statistical software and automatically saved in the cloud. The patient's height was recorded using the hospital's anthropometer during the initial admission. The BMI was calculated directly using the formula provided in the statistical software [17].

Intervention fidelity

The fidelity of the intervention was evaluated by a nurse with a master's degree who was independent of the multidisciplinary team. The intervention group and the control group were evaluated separately at each intervention. A self-designed scale, based on other similar Chinese research [25], was used for the evaluation and checked by 5 experts. The scale consisted of 11 items. The first 10 items had the same scoring criteria: selecting'yes'earned 1 point, while selecting'no'earned 0 points. The total score was calculated by summing the scores of all items. The last item required recording the total duration of each intervention. The scale primarily assessed the multidisciplinary team members'implementation of the intervention in two aspects: diet knowledge education and implementation. Its purpose was to quantify the extent to which the intervention was carried out according to established norms and plans.

Statistical analysis

We utilized IBM SPSS Statistics 21.0 software for the analysis of statistical data. Descriptive statistics and percentages of patients in various demographic and clinical groups were calculated. Mean and standard deviation values were used to compare DSMBQ total and dimension scores, SUPPH and FACT-B scores, and BMI. To assess the baseline balance between the two groups, independent sample t-tests, chi-square tests, or Mann–Whitney U tests were employed, depending on the distribution of the data and whether homogeneity of variance was met. The Shapiro–Wilk test was used to check if the scores of the two groups at different time points followed a normal distribution. If the data was balanced, repeated ANOVA was utilized. Otherwise, a generalized estimating equation (GEE) was used to analyze the effects of time, group, and interaction. A statistically significant difference was indicated when P < 0.05, with an α level of 0.05, and all tests were two-sided [17].

Ethical consideration

The ethical consideration for this study was approved by the ethics committee of the second affiliated hospital of Air Force Medical University (No: K202305 - 41). Patients were provided with information about the purpose, procedure, content, possible benefits, and risks of the study. They were also informed of their right to withdraw from the study at any time, with no interference with their treatment and medical services. Once patients agreed to participate, they were given a paper-based informed consent form to read and sign in person. Data storage was the responsibility of a chief nurse, who was independent from other members. The data was stored electronically and only accessible by the chief nurse using an authorized USB with a password, ensuring confidentiality.

Results

We conducted a 3-month recruitment period from November 2023 to January 2024. A total of 218 patients met the inclusion criteria, of which 88 (40.4%) were enrolled in the study. Of these, 44 patients were assigned to the intervention group. Four patients dropped out, resulting in 40 (90.9%) completing the intervention. The reasons for attrition included: changing the treatment plan (n = 1), being referred to a local hospital for personal reasons (n = 1), inability to tolerate the adverse reactions of chemotherapy (n = 1), and loss of contact (n = 1). In the control group, 44 patients were also included. Five patients were lost to follow-up, resulting in 39 (88.6%) completing the study. The reasons for attrition in this group included: adjusting the treatment plan due to poor chemotherapy response (n = 2), inability to complete the intervention due to disease progression (n = 2), and family members'refusal to allow the patient to continue (n = 1). In total, 79 female patients successfully completed the entire intervention at the three time points of T0, T1, T2, and T3, as indicated in Fig. 1. There were no obvious adverse events or side effects in each group.

Fig. 1

Flow diagram for participants recruitment in this intervention

Participant characteristics and baseline outcome variables

The age average of the 79 participants was 46.43 years (standard deviation = 5.35), and the average BMI was 22.86 kg/m² (standard deviation = 2.59). The majority of patients (n = 67, 84.8%) had spouses, with most of the females (n = 57, 72.2%) having more than 2 children. Only a few participants (n = 17, 21.5%) had primary school education or below. A very small number of patients'(n = 11, 13.9%) per capita monthly household income exceeded 5000 yuan. Some participants (n = 32, 40.5%) lived in urban areas, while several (n = 14, 17.7%) were employed. Almost half of the females were at the menopausal stage (n = 33, 41.8%) and had been diagnosed one month ago (n = 35, 44.3%). The majority of patients (n = 71, 89.9%) had unilateral breast cancer, with only a few (n = 13, 16.5%) being diagnosed with cancer stage III or higher. Many of them (n = 56, 70.9%) received adjuvant chemotherapy.

Before the intervention, a comparison of demographic and clinical data between the intervention and control groups at baseline revealed no statistically significant differences in all indicators (P > 0.05). Additionally, there were no statistically significant differences in the total scores and scores for each dimension of dietary management behavior, self-care self-efficacy, and quality of life between the two groups at baseline (P > 0.05), as indicated in Table 1.

Table 1 Demographic, clinical characteristics and indicators of all participants (N = 79)

Effectiveness of the intervention on dietary management behavior

Before and after the early multidisciplinary team interventions, there was a statistically significant intergroup effect between the intervention and control group in the total score of dietary management behavior (P < 0.01). The time effect was also statistically significant (P < 0.01). Additionally, there was an interaction effect between the intervention factor and time factor (P < 0.01). When considering the scores of the four dimensions, there was a statistically significant intergroup effect between the intervention and control group (P < 0.05), as well as a statistically significant time effect (P < 0.05). In each dimension, there was an interaction effect between the intervention factor and time factor (P < 0.05), as demonstrated in Table 2.

Table 2 Scores and differences of the variables between two groups at different time points

Effectiveness of the intervention on self-care self-efficacy

Before and after the intervention, the intergroup effect between the intervention and control groups on the total score of self-care self-efficacy was statistically significant (P < 0.05). Additionally, the time effect was statistically significant (P < 0.01). Furthermore, an interaction effect was observed between the intervention factor and the time factor (P < 0.01), as indicated in Table 2.

Effectiveness of the intervention on quality of life

Before and after the intervention, the intergroup effect between the intervention and control groups on the total score of quality of life was found to be statistically significant (P < 0.01). Additionally, the time effect was also found to be statistically significant (P < 0.01). Moreover, an interaction effect between the intervention factor and time factor was observed (P < 0.01), as demonstrated in Table 2.

Effectiveness of the intervention on BMI

Before and after the intervention, there was no statistically significant intergroup effect between the intervention and control group in BMI (P > 0.05). However, the time effect was found to be statistically significant (P < 0.01). Table 2 demonstrates the presence of an interaction effect between the intervention factor and the time factor (P = 0.01).

Performance of intervention fidelity

There were no significant differences in fidelity scores and average intervention duration between the intervention group and the control group (all P > 0.05), as shown in Table 3.

Table 3 Scores of the fidelity assessment and average intervention time between two groups

Discussion

To the best of our knowledge, this is the first study to develop and implement early multidisciplinary team interventions aimed at enhancing dietary management behavior, self-care self-efficacy, and quality of life among breast cancer patients undergoing chemotherapy. Combining the characteristics of BC patients with subsection about the intended meaning of multidisciplinary team interventions, we designed a holistic approach by different healthcare professionals, encompassing physiological, psychological, social and cultural elements to effectively facilitate dietary management behavior in this study. This pilot study had a small sample size and a short-term follow-up. Although some measures, such as dietary habits adjustment and self-care self-efficacy, did not show significant differences at the 3-month mark after the intervention compared to baseline, and there were no significant differences in intervention factors, such as BMI, between the two groups, this intervention can still serve as a valuable reference for future research on nutritional management and lifestyle promotion.

Effects on BC patients’ dietary management behavior

The intergroup effect between two groups and the time effect of dietary management behavior (total and four dimension scores) were statistically significant. There was also an interaction effect, which supported the previous hypothesis. Some evidence [9, 10, 26] suggests that providing professional early dietary intervention during chemotherapy can significantly reduce the risk of malnutrition and improve the quality of life for later recovery. However, there is not enough validation in the BC population, and there is a lack of high-quality RCT. Additionally, there are few interventions involving dietary management of cancer patients designed from a biopsychosocial perspective, most of studies [15, 27] measured the specific dietary changes, including quantity and quality of food consumption, and there is a lack of multidisciplinary team interventions. This study chose the intervention outcome of dietary management behavior based on the theoretical guidance of ITHBC and initially conducted training for multidisciplinary team members to ensure the authority and comprehension of the intervention as much as possible. Moreover, the interaction effect observed may be due to the fact that the population included in the study consisted of BC patients receiving early or mid-stage chemotherapy, and the adverse reactions at the beginning are mostly manifested as nausea, vomiting, loss of appetite, and other gastrointestinal symptoms related to dietary intake. At this time, dietary management intervention may be one of the most important, safe, and cost-effective ways to regulate health. Additionally, patients during chemotherapy are weak and fatigued, and their physical functions have not yet fully recovered. Compared with survivors, it is not suitable to add too much exercise from the perspective of health behavior change. The above information may reflect the relevance (intergroup effect) and durability (time effect) of early intervention in improving the dietary management behavior of BC patients during chemotherapy. Unlike the other three dimensions, there was no statistically significant difference in the dietary habits adjustment score for patients in the intervention group at 3 months post-intervention compared to baseline. This may be attributed to the fact that, by this time, patients had largely completed the entire chemotherapy cycle and entered the survival period. With the progression through different stages of chemotherapy and changes in dietary experiences [28], patients'emphasis and demand for dietary habit adjustments also evolved. During the early and middle stages of chemotherapy, gastrointestinal symptoms are typically the most severe and frequent adverse effects [29], significantly impacting daily food intake. To ensure the smooth progress of chemotherapy, it is crucial to maintain standard nutritional intake to support body function and physical strength. Therefore, patients may be more inclined to adjust their diet structure and increase food intake to withstand the high energy demands of chemotherapy. In the survival period, patients generally have better physical status and more time to focus on food quality, and dietary restrictions may be less stringent than during chemotherapy.

Effects on BC patients’ self-care self-efficacy

The intergroup effect between the two groups and the time effect on self-care self-efficacy were statistically significant, with an interaction effect supporting the initial hypothesis. However, this differs from the results of a previous study [30]. That study recruited patients with head and neck cancer, colorectal cancer, lymphoma, and BC for a RCT using the e-Health app Oncokompas, which provided participants with health self-management techniques independent of healthcare staff and monitored cancer-specific symptoms. The results indicated that self-efficacy in patients from both groups did not significantly change over time at baseline, 1 week, 3 months, and 6 months post-intervention. The discrepancies between our study and that study [30] may be due to differences in the intervention population and content. The previous study included patients with both solid tumors, including BC, and hematologic malignancies. Solid tumor lesions are relatively localized, resulting in a lighter chemotherapy burden, and the early and middle stages of chemotherapy primarily present with gastrointestinal symptoms. Consequently, the specific needs related to diet and nutrition in self-management are higher, and these patients have a better physical basis for dietary self-management. In terms of intervention content, the previous study [30] focused mainly on physiological factors such as symptom management, life skills, and health monitoring, with relatively less targeted support at the psychosocial level. In our study, the significant effect on self-care self-efficacy disappeared 3 months post-intervention compared to baseline. This could be attributed to the fact that the intervention cases, examples, and demonstration methods were all based on the chemotherapy period. Whether these are applicable to dietary management during the survival period after the end of chemotherapy remains to be verified.

Effects on BC patients’ quality of life

The intergroup effect between the two groups and the time effect on the quality of life were statistically significant, with an interaction effect also observed. Additionally, the score differences at each time point after the intervention, compared to baseline, were statistically significant. While some studies have explored the impact of lifestyle interventions on the quality of life in BC patients, the majority of these populations were survivors who had completed treatment [31]. The results of this study differ from those of another study [32], which aimed to prevent chemotherapy-induced weight gain by providing a combination of resistance and aerobic training along with a low energy density diet to BC patients within 3 weeks of starting neoadjuvant chemotherapy. That study assessed health-related quality of life at baseline, mid-chemotherapy (3 months), and 6 months post-chemotherapy, and found that only the"vitality"subscale improved significantly more in the intervention group than in the control group at the end of chemotherapy.

The possible reasons for these differences may be attributed to the heterogeneity of assessment tools, intervention targets, and content. The previous studies used the SF- 36, a universal quality of life assessment tool, whereas this study utilized FACT-B, which is specific to BC patients. Different validity between these tools may contribute to varying results. Additionally, although the intervention in this study also involved"weight management,"it encompassed eight themes from psychological, social, and behavioral perspectives. The aim was to provide a comprehensive dietary intervention through the collaboration of multidisciplinary team members, helping patients develop the willingness and ability to manage their diet, thus laying the foundation for improving their quality of life in the long term. In terms of intervention content, Karen et al. [30] focused mainly on physical exercise and food types, emphasizing the impact of lifestyle intervention on the physiological health of BC patients. As the definition of quality of life becomes increasingly multifaceted, incorporating a diverse range of intervention content may enhance overall quality of life more effectively.

Effects on BC patients’ BMI

The intergroup effect on BMI between the two groups was not statistically significant, and the intervention group showed no statistically significant differences compared with baseline at the three time points. The results of this study differ from those of a RCT conducted by Parekh et al. [33]. In that study, BC survivors who had finished chemotherapy received six nutrition education interventions under the theme of"Healthy Eating and Living Against Breast Cancer,"and the intervention group had a significantly lower risk of higher BMI at the third month post-intervention compared to baseline. The reason for the difference may lie in the primary focus of Parekh's study [33], which aimed to enhance nutritional literacy among BC survivors by providing food and nutrition knowledge. Their intervention focused on understanding portion sizes and food groups, continuously measuring the relationship between intake and nutritional literacy across different food groups. In contrast, while our study also provided dietary and nutritional knowledge about food groups and intake, it was primarily from the perspective of health behavior change. We were more concerned with whether patients could independently develop good dietary habits and positive lifestyle management patterns, aiming to stimulate patients'awareness of participating in dietary management and enhancing their ability to practice. As a result, the positive effect on patients'BMI between the groups may not have been significant. Additionally, unlike patients in the survival stage, BC patients who have just received chemotherapy may tend to lose confidence in lifestyle management due to the immense pressure of diagnosis and treatment, and may not know how to adjust their diet [34]. These patients need to enhance their awareness of health management and adopt dietary management behaviors, laying the foundation for long-term lifestyle management during the survival stage. After treatment, surviving patients typically have developed autonomy and good lifestyle management experiences during chemotherapy, and most have some knowledge of a healthy diet. On this basis, implementing more professional and comprehensive dietary education can more easily help them maintain a healthy BMI. This intervention targeted females in the early and middle stages of chemotherapy, and its long-term positive effect on BMI in the survival stage may be difficult to demonstrate immediately, necessitating future tracking.

Limitations

There are some limitations to this research. Firstly, this was a single-centered intervention with a small sample size, and participants were all from a hospital in northwest China, which may limit the generalizability of the findings. In the future, a multi-center trial encompassing the east, west, north, and south of China should be conducted to further verify the intervention's effect. Secondly, this study only evaluated the short-term effectiveness within 3 months post-intervention, and long-term effects should be continually assessed. Additionally, the BC patients included in this study were in the early and middle stages of chemotherapy, and most had not yet completed or had just completed chemotherapy at the 3-month post-intervention mark. This timing may not be optimal for predicting the incidence of malnutrition or other related outcomes. We plan to address this in the next long-term follow-up. Thirdly, although this pilot study primarily focused on the perspective of health behavior change, aim to trigger the motivation and improve the knowledge of dietary self-management, the future intervention outcomes should be supplemented with laboratory data, specific dietary changes or nutritional status assessments. Qualitative interviews could also be added to explore patients'dietary experiences and their feelings about participating in the intervention process. Fourthly, the inclusion scope of cancer stage of BC females may influence the effect of the intervention. More future studies are needed to deeply explore its potential relationship. Lastly, due to limitations in time, manpower, and material resources, intention-to-treat and sensitivity analyses were not performed in this pilot test, which may affect the accuracy of evaluating the intervention's effect. We plan to incorporate these analyses after 6-month and 1-year follow-up results are available.

Conclusions

From the perspective of health behavior change and lifestyle self-management, we assessed the effectiveness of early multidisciplinary team interventions during the early and middle stages of chemotherapy for Chinese BC patients, guided by the ITHBC. Based on previous evidence and the emerging trend of multidisciplinary collaboration, we are committed to providing professional, scientific, and comprehensive dietary management interventions to BC patients undergoing chemotherapy as early as possible, with nurses playing a core role in the multidisciplinary team. The results suggested that this intervention can improve the dietary management behavior and quality of life of BC patients, but the long-term effects on self-care self-efficacy and BMI need further exploration. In future clinical practice, nurses should pay attention to the nutritional problems of BC patients, and train and organize multidisciplinary team to provide early dietary management interventions during chemotherapy to reduce the risk of malnutrition as much as possible. This approach lays a theoretical and practical foundation for survival lifestyle management. For future research, we recommend that early interventions continue to be tailored to different stages of chemotherapy and the occurrence of adverse reactions. This strategy is also significant in responding to national health departments'efforts to improve the health self-management of patients with chronic diseases and reduce medical financial expenditure.