The role of patient age in fertility preservation among women with breast cancer: biological mechanisms and clinical implications.

Breast cancer (BC) is the most common malignancy among women of reproductive age. Improved survival has shifted clinical focus toward survivorship and fertility preservation. While the gonadotoxic effects of anticancer therapy are well recognized, the influence of patient age on fertility outcomes remains insufficiently integrated into clinical decision-making. This review synthesizes current evidence from clinical, molecular, and translational studies addressing the relationship between age, ovarian reserve, and reproductive outcomes in women with BC undergoing gonadotoxic treatments. It also examines how age interacts with BRCA mutations, endocrine therapy, and fertility preservation strategies. Age critically modulates the ovarian response to chemotherapy, the extent of oocyte depletion, and recovery of ovarian function. Younger patients show higher resilience and better success with fertility preservation methods such as oocyte, embryo, or ovarian tissue cryopreservation. Conversely, older women face accelerated follicular depletion, reduced AMH levels, and delayed conception due to prolonged adjuvant therapy. BRCA-related DNA repair defects further exacerbate age-related decline. Patient age represents the most decisive factor guiding fertility preservation in BC care. Incorporating age-specific counseling and early referral into multidisciplinary oncofertility practice is essential to optimize reproductive outcomes and align survivorship with future family planning goals.