# Achieving Pregnancy After Early Hormone Receptor-Positive Breast Cancer: Recent Evidence and Clinical Considerations

## TL;DR

Young women with early hormone receptor-positive breast cancer can safely attempt pregnancy after treatment, with no increased short-term cancer risk.

## Contribution

The paper provides updated clinical guidance and evidence from the POSITIVE trial on the safety of pregnancy after hormone receptor-positive breast cancer.

## Key findings

- Temporary interruption of endocrine therapy to attempt pregnancy does not increase short-term recurrence risk in selected patients.
- Pregnancy and live birth rates are comparable to the general population, and breastfeeding is feasible without adverse cancer outcomes.
- Fertility preservation and assisted reproductive technologies are safe in the short term and do not worsen oncologic outcomes.

## Abstract

Breast cancer is increasingly diagnosed in young women who have not yet completed their families. Historically, pregnancy after breast cancer was discouraged due to concerns about recurrence risk and the impact of the interruption of adjuvant therapy. This review summarizes the current evidence and considerations on achieving pregnancy following a diagnosis of hormone receptor-positive breast cancer, with a focus on findings from the prospective POSITIVE trial. Available data show that temporary interruption of endocrine therapy to attempt pregnancy is feasible and does not increase short-term recurrence risk in carefully selected patients. Pregnancy and live birth rates are comparable to those of the general population, and the use of fertility preservation and assisted reproductive technologies appears safe in the short term. Breastfeeding is also achievable for many women and does not appear to adversely affect outcomes. While these findings are reassuring, uncertainties remain regarding long-term safety, the impact of a break in endocrine therapy in women with higher-risk disease, BRCA mutation carriers, and new standard of care adjuvant therapies. Individualized counselling remains essential.

An increasing number of young women with hormone receptor-positive (HR+) early breast cancer desire pregnancy after treatment. Prolonged adjuvant endocrine therapy, concerns regarding recurrence risk, and treatment-related fertility decline have historically complicated reproductive decision-making in this population. This narrative review synthesizes current evidence on pregnancy after early HR+ breast cancer, with particular emphasis on prospective data from the POSITIVE trial. We examine the safety of temporary endocrine therapy interruption, the impact of assisted reproductive technologies (ART) in achieving pregnancy, breastfeeding feasibility and impact, hormonal predictors of fertility, pregnancy outcomes and considerations for special populations, including BRCA mutation carriers. Retrospective studies have suggested no adverse survival impact associated with pregnancy after breast cancer. The POSITIVE trial provides prospective evidence that temporary interruption of endocrine therapy to attempt pregnancy does not increase short-term recurrence risk in selected patients. Approximately three-quarters of participants achieved pregnancy. Fertility preservation and ART were commonly used and were not associated with worse short-term oncologic outcomes. Biomarkers such as anti-Müllerian hormone offer supportive but imperfect prediction of fertility potential. Breastfeeding was feasible for many women and did not adversely affect breast cancer outcomes. Available data among BRCA mutation carriers are reassuring but largely observational. Current evidence supports the safety and feasibility of pregnancy after early HR+ breast cancer in carefully selected patients. However, longer follow-up, inclusion of higher-risk populations, and evaluation of newer therapies are needed. Individualized, multidisciplinary counselling remains central to informed decision-making.