A new study published in the New England Journal Of Medicine suggests that temporary suspension of hormone medication to seek pregnancy did not give a higher short-term risk of breast cancer events, including distant recurrence, than the external control cohort among select women with prior hormone receptor-positive early breast cancer.
There is a dearth of prospective evidence on the risk of recurrence in women with hormone receptor-positive early breast cancer who temporarily quit endocrine therapy to try to conceive. As a result, Ann Partridge and colleagues undertook this research to examine recurrence after temporarily discontinuing medication.

Researchers performed a single-group experiment to assess the brief suspension of adjuvant endocrine treatment to seek conception in young women with prior breast cancer. Eligible women were 42 or younger, had stage I, II, or III illness, had undergone adjuvant endocrine treatment for 18 to 30 months, and wanted to have a baby. The number of breast cancer occurrences during follow-up was the major end point. The primary analysis was scheduled for 1600 patient-years of follow-up. The incidence of 46 breast cancer incidents over this time period met the predetermined safety threshold. The results of breast cancer in this treatment-interrupted group were compared to those in an external control cohort of women who would have satisfied the admission requirements for the study.
The key findings of this study were:
1. The median age of the 516 women was 37, the median time from breast cancer diagnosis to enrolment was 29 months, and 93.4% had stage I or II illness.
2. 368 (74.0%) of the 497 women monitored for pregnancy status had at least one pregnancy, and 317 (63.8%) had at least one live birth.
3. There were 365 babies born in total. 44 patients experienced a breast cancer incident during 1638 patient-years of follow-up (median follow-up, 41 months), a result that did not surpass the safety threshold.
4. The 3-year incidence of breast cancer events in the treatment-interrupted group was 8.9% and 9.2% in the control cohort.
There is no increase in the short-term risk of breast cancer events among select women with past hormone receptor-positive early breast cancer when endocrine medication is temporarily interrupted to seek pregnancy.
Reference:
Partridge, A. H., Niman, S. M., Ruggeri, M., Peccatori, F. A., Azim, H. A., Jr., Colleoni, M., Saura, C., Shimizu, C., Sætersdal, A. B., Kroep, J. R., Mailliez, A., Warner, E., Borges, V. F., Amant, F., Gombos, A., Kataoka, A., Rousset-Jablonski, C., Borstnar, S., Takei, J., … Pagani, O. (2023). Interrupting Endocrine Therapy to Attempt Pregnancy after Breast Cancer. In New England Journal of Medicine (Vol. 388, Issue 18, pp. 1645–1656). Massachusetts Medical Society. https://doi.org/10.1056/nejmoa2212856