“While breast cancer is most commonly diagnosed in middle-aged and older women, in the United States, about 5 percent of new diagnoses each year occur in women aged 40 or younger. These younger patients face some unique considerations, including fertility”, said the North American study’s lead author, Ann Partridge, M.D., M.P.H., vice-chair of medical oncology at Dana-Farber Cancer Institute and professor of medicine at Harvard Medical School.
Forty to sixty percent of patients who are diagnosed with breast cancer at age 40 or younger are concerned about their future fertility, especially if the disease occurs before they could decide whether to become a mother or not.
Only about 5 to 10 percent of younger breast cancer patients go on to become pregnant. While some retrospective studies have shown that pregnancy after cancer is feasible and safe, many women are concerned that breast cancer treatment will make it difficult to conceive or that pregnancy might exacerbate a woman’s cancer.
Pausing Cancer Treatment to Conceive
Young women with early-stage hormone receptor (HR)-positive breast cancer are often treated with endocrine therapy, such as ovarian function suppression, aromatase inhibitors, or selective estrogen receptor modulators. To examine the impact of pausing endocrine therapy to pursue pregnancy, researchers designed the single-arm POSITIVE clinical trial (Pregnancy Outcome and Safety of Interrupting Therapy for Women with Endocrine Responsive Breast Cancer).
From December 2014 through December 2019, 518 women aged 42 or younger who desired to become pregnant enrolled in the study, opting to pause endocrine therapy for approximately two years to try to get pregnant. Before pausing their treatment, women had completed between 18 and 30 months of adjuvant endocrine therapy.
At a median follow-up of 41 months, 44 participants had experienced a recurrence of breast cancer. The three-year rate of recurrence was 8.9 percent, similar to the 9.2 percent rate in an external control cohort from the other trials, which examined adjuvant endocrine therapy in premenopausal women.
Of 497 women followed for pregnancy status, 368 (74 percent) had at least one pregnancy, and 317 (63.8 percent) had at least one live birth, with a total of 365 babies born. These rates of conception and childbirth were on par with or higher than rates in the general public, according to researchers.
Trial participants were strongly recommended to resume endocrine therapy after a pregnancy attempt or success. To date, 76.3 percent have resumed their therapy, the authors said.
The study provides encouraging guidance to younger women diagnosed with breast cancer who may be hoping to have children. Any such decisions should be made in close consultation with health professionals, they noted.
The POSITIVE trial provides important data to support young women with HR-positive early breast cancer who are interested in a pregnancy and taking a break from endocrine therapy to pursue one.
Pregnancy after breast cancer is a very personal decision for which, ideally, a woman should take into account not only her desire to carry a pregnancy, but her baseline fertility, prior and current treatment, and any fertility preservation strategy she may have pursued, as well as the underlying risk of cancer recurrence she faces.
The researchers are continuing to follow the study participants to assess recurrence risk over time. They noted that the short follow-up to date is a limitation of the POSITIVE study, as HR-positive breast cancer can recur many years after an initial diagnosis.
- Breast Cancer Patients Who Interrupted Endocrine Therapy to Pursue Pregnancy Did Not Experience Worse Short-term Recurrence Rates
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