Impact of fertility concerns on endocrine therapy decisions in young breast cancer survivors

Background The diagnosis and treatment of breast cancer can have profound effects on a young woman's family planning and fertility, particularly among women with hormone receptor–positive breast cancer. Methods The Young Women's Breast Cancer Study was a multicenter cohort of women aged 40 years or younger and newly diagnosed with breast cancer from 2006 to 2016. Surveys included assessments of fertility concerns, endocrine therapy (ET) preferences, and use. Characteristics were compared between women who reported that fertility concerns affected ET decisions and those who did not. Logistic regression was used to identify factors associated with having an ET decision affected by fertility concerns. Results Of 643 eligible women with hormone receptor–positive, stage I to III breast cancer, one‐third (213 of 643) indicated that fertility concerns affected ET decisions. In a multivariable analysis, only parity at diagnosis was significantly associated with fertility concerns affecting ET decisions (odds ratio for nulliparous vs ≥2 children, 6.96; 95% confidence interval, 4.09‐11.83; odds ratio for 1 vs ≥2 children, 5.30; 95% confidence interval, 3.03‐9.87). Noninitiation/nonpersistence was higher among women with fertility concerns versus those without fertility concerns (40% vs 20%; P < .0001). Among women with fertility‐related ET concerns, 7% (15 of 213) did not initiate ET, and 33% (70 of 213) were nonpersistent over 5 years of follow‐up. Of these women, 66% (56 of 85) reported 1 or more pregnancies or pregnancy attempts; 27% (15 of 56) had resumed ET at the last available follow‐up through 5 years. Conclusions Concern about fertility is a contributor to adjuvant ET decisions among a substantial proportion of young breast cancer survivors. Ensuring family planning is addressed in the setting of ET recommendations should be a priority throughout the cancer care continuum.