CHICAGO—Breast cancer survivors, including those with estrogen receptor (ER)-positive tumors, can safely become pregnant, according to a new study.
Women who became pregnant after an early breast cancer diagnosis did not have a higher chance of cancer recurrence and death than those who did not become pregnant.
About half of young women with newly diagnosed breast cancer express interest in having children, yet less than 10% of them subsequently become pregnant, said lead author Matteo Lambertini, MD, a medical oncologist and ESMO fellow at the Institut Jules Bordet in Brussels, Belgium, at a press briefing at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting (abstract LBA10066).
“Many patients and physicians remain concerned about the potential detrimental prognostic impact of pregnancy in breast cancer survivors, particularly in those with ER-positive disease,” said Lambertini. “Our findings confirm that pregnancy after breast cancer should not be discouraged, even for women with ER-positive cancer.”
Lambertini presented the analysis of a long-term follow-up of 1,207 patients from a multicenter retrospective study. The study included women who were diagnosed with non-metastatic breast cancer before 2008, under the age of 50. The majority (57%) had ER-positive cancer. More than 40% had poor prognostic factors, such as large tumor size and cancer that had spread to the axillary lymph nodes.
Among the 1,207 patients, 333 became pregnant and 874 did not. The median time from diagnosis to conception was 2.4 years.
After a median follow-up of about 10 years from cancer diagnosis, there was no disease-free survival difference between pregnant and non-pregnant women, irrespective of ER status.
There was no overall survival difference between the two cohorts in patients with ER-positive disease, but survivors of ER-negative breast cancer who became pregnant had a 42% lower chance of dying than those who did not become pregnant.
Pregnancy could protect ER-negative breast cancer patients through either immune system mechanisms or hormonal mechanisms, suggested Lambertini.
Abortion did not have any impact on outcome, irrespective of ER status. Among 25 women who reported having breastfed their newborn, the results suggest that breastfeeding is feasible, even after breast surgery. A small number of patients used assisted reproductive technologies, and this appears to be safe in breast cancer survivors, he said.
A large clinical trial now under way is designed to investigate the impact of interrupting adjuvant hormone therapy to allow for pregnancy in women with ER-positive breast cancer and will provide further insight on the impact of reproductive technologies and breastfeeding.
“Our findings should serve as strong basis for counseling women inquiring into the safety of future conception,” said Lambertini.
ASCO expert Erica L. Mayer, MD, MPH, assistant professor of medicine at Harvard Medical School, agreed that “the long-term follow-up data provide great reassurance for young breast cancer survivors and their physicians that choosing pregnancy is safe and acceptable.”
Lambertini noted that the decision for how long a breast cancer survivor should wait before becoming pregnant should be based on the individual woman’s personal risk for recurrence, particularly for women who need adjuvant hormone therapy.