POSITIVE - BIG time for baby

Young women with breast cancer can safely have a baby.

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I would like to have a baby. Can I interrupt my breast cancer endocrine treatment without increasing the risk of cancer coming back?

This is a question many young women ask their physicians and that BIG researchers are partially able to answer thanks to the POSITIVE – BIG Time for Baby study.

The POSITIVE academic study – which involves 518 women aged 42 or younger, and 116 hospitals from 11 research groups across 20 countries – was launched in order to understand whether women, who desire to, can interrupt their endocrine treatment to try to have a baby, without increasing the risk of cancer recurrence.

First results, presented at the 2022 San Antonio Breast Cancer Symposium, show that young women with breast cancer who paused their endocrine treatment to try to get pregnant were able to do so without increasing the risk of relapse at 3 years after recruitment. The rates of breast cancer coming back (8.9%) were similar to women who did not interrupt their treatment (9.2%), and most were able to conceive and deliver healthy babies, with a total of 365 babies being born.

About 20% of patients with breast cancer are diagnosed during their reproductive years and an estimated 100,000 women aged 42 or younger are diagnosed with hormone-sensitive breast cancer every year, so called (estrogen, progesterone) hormone receptor-positive (HR+) disease, meaning the cancer cells are fed by their own hormones.

These women are therefore treated with endocrine therapy, which blocks the natural production of hormones and/or interferes with the effect of hormones on breast cancer cells in order to reduce risks of recurrence. Endocrine therapy may be prescribed for 5-10 years and impacts the ovaries, preventing conception while on treatment.

However, women with breast cancer may not be able to wait so long before considering pregnancy.

This study assesses whether it is safe for young women who had HR+ breast cancer and who wish to become mothers to interrupt their endocrine treatment and have a baby.

The first results of POSITIVE are very reassuring, but long-term follow-up is essential. Researchers will continue to follow patients to evaluate the risk of breast cancer returning over time, as well as to ensure that the women will complete their treatment following the planned pause.