A new study examining the real-world implications of interrupting endocrine therapy (ET) for pregnancy in breast cancer patients has revealed concerning gaps in post-pregnancy care. The research highlights the need for improved adherence to ET resumption protocols to optimise long-term outcomes for young breast cancer survivors.
Utilising the Oncoshare database, which integrates medical records from both community and academic healthcare systems in California, USA, researchers identified 215 women diagnosed with stage 0 to III breast cancer between January 2000 and October 2024 who subsequently became pregnant. The study analysed ET usage, breast imaging adherence, and recurrence rates over a median follow-up of 9.7 years.
Of the 163 women with hormone receptor (HR)-positive breast cancer, 30% never initiated ET. Among those who did, the median ET duration was 4.5 years, and only 32% completed the recommended five-year course. For women who paused ET for pregnancy, the median interruption lasted 21 months. Notably, only 34% had resumed ET by two years post-delivery, and 48% by ten years.
The study found that women who resumed ET were more likely to have had invasive disease and received chemotherapy or radiotherapy. However, 19% of the cohort experienced subsequent breast cancer events within ten years, with locoregional recurrences being the most common. Distant recurrences and breast cancer-related deaths were rare, but the overall recurrence rate was double that observed in older patient cohorts.
The findings underscore a significant gap in post-pregnancy ET resumption, potentially contributing to suboptimal outcomes. While previous clinical trials like the POSITIVE study reported high ET resumption rates and low recurrence, this real-world data suggests that oncology practices may struggle to maintain adherence outside controlled trial settings.
The study highlights the need for targeted interventions to re-engage breast cancer survivors in guideline-concordant care post-pregnancy. Further research should explore the barriers to ET resumption, such as the competing demands of early parenthood and limited patient understanding of ET’s importance. Addressing these issues could improve long-term survival outcomes for young breast cancer patients.
For detailed methodology and statistical analysis, refer to the full study published in JAMA Oncology.
Paper: Ransohoff, J D., et al. Research Letter: Endocrine Therapy Interruption, Resumption, and Outcomes Associated With Pregnancy After Breast Cancer. JAMA Oncology. Published online February 13, 2025. doi:10.1001/jamaoncol.2024.6868
