The impairment of ovarian function caused by chemotherapy that results in temporary (3 consecutive months) or permanent amenorrhea is called chemotherapy-induced amenorrhea (CIA). The effect of chemotherapy on menstruation is divided into: 1) no effect: menstrual disorders without amenorrhea; 2) recovery after amenorrhea: resumption of menstruation after more than 3 months of transient amenorrhea; 3) non-recovery of amenorrhea: amenorrhea for more than 1 year and not recovering. The proportion of female breast cancer patients who develop amenorrhea increases significantly with age. According to the relevant literature, the proportion of CIA occurring in patients <40 years old is 22%-61% and in patients ≥40 years old is 61%-97%. The effect of chemotherapy on the ovaries is mainly the reduction of follicles and luteal hypofunction, and the damage to the ovaries is positively correlated with the destruction of follicular structures. When large follicles disappear, pituitary feedback increases gonadotropin release, causing small follicles to replenish into a larger pool of follicles that continue to be destroyed by the drug, and this vicious cycle causes a decline in the number of small follicles leading to ovarian failure. Chemotherapy also causes a significant reduction in follicle cell gonadotropin-releasing hormone receptor (GnRHR) mRNA expression and diminished or even absent transcriptional proteins, so that follicle development and maturation are hindered. In adult ovaries, the number of follicles decreases with age, so they are more susceptible to drugs and more sensitive to chemotherapeutic agents. Once follicles are damaged during chemotherapy, this can lead to a decrease in follicle number, disappearance or even fibrosis of ovarian tissue. Because germinal stem cells have not been found in the adult ovary, damaged follicles cannot regenerate. For most women younger than 35 years of age, menstruation can resume within 2 years after completion of adjuvant chemotherapy.