Fig. 2

Kaplan-Meier survival estimates showing the time to biochemical amenorrhea in premenopausal breast cancer patients following chemotherapy. The median time to biochemical amenorrhea was 18 months, which indicates that half of the patients had hormonal changes suggestive of ovarian insufficiency within this period. The extended median duration for biochemical amenorrhea presumably indicates the delayed hormonal response in relation to clinical manifestations, possibly affected by varying evaluation intervals and the intrinsic hormonal fluctuations. This delayed onset, in comparison to clinical amenorrhea (8 months), implies that cessation of menstruation alone may not be a reliable indicator of ovarian suppression; continuous monitoring of hormonal status is necessary in these patients. The shaded area is the 95% confidence interval, which is the uncertainty in biochemical amenorrhea estimates. These findings highlight the need for combining biochemical assessments along with clinical evaluation for precisely assessing ovarian function following chemotherapy