Researchers investigated the risk of breast cancer recurrence in young women with hormone receptor-positive early breast cancer who temporarily discontinued endocrine therapy to attempt pregnancy. They conducted a single-group trial with 516 eligible women aged 42 or younger, who had received adjuvant endocrine therapy for 18 to 30 months and desired pregnancy. The primary endpoint was the number of breast cancer events during follow up.

Results showed that at 1,638 patient-years of follow up (median follow-up, 41 months), 44 patients had a breast cancer event, which did not exceed the safety threshold. The 3-year incidence of breast cancer events was similar in the treatment-interruption group (8.9%) and the control cohort (9.2%). This suggests that temporary interruption of endocrine therapy for pregnancy did not pose a higher short-term risk of breast cancer events compared with the control group.

Reference: Partridge AH, Niman SM, Ruggeri M, et al. Interrupting Endocrine Therapy to Attempt Pregnancy after Breast Cancer. N Engl J Med. 2023;388(18):1645-1656. doi: 10.1056/NEJMoa2212856.