Pregnancy after breast cancer treatment is safe

Pregnancy after breast cancer does not increase the risk of recurrence, a new study by Belgian researchers has determined.

Findings from the retrospective study of 1,200 women in Belgium will provide reassurance to breast cancer survivors who are contemplating pregnancy. In the 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.

The researchers note that breast cancer is the most common cancer in women of reproductive age, and say that as the average age of childbearing increases, breast cancer in young women may occur before they are finished planning their families. “Although half of young women with newly diagnosed breast cancer report interest in having children, less than 10% become pregnant after treatment… In fact, of all cancer survivors, breast cancer survivors are the least likely to have a baby after diagnosis,” the authors of the new study state.

Doctors and patients have long been concerned that pregnancy could increase the chance of breast cancer recurrence, particularly for women with a certain type of breast cancer that is oestrogen receptor (ER)-positive. The fear has been that alterations in hormone levels as experienced during pregnancy could coax any remaining cancer cells to grow. In addition, there is the concern regarding the need to interrupt necessary post-surgery hormone therapy before women try for a pregnancy. This hormone therapy helps prevent cancer recurrence, and it is recommended that women receive it for between five and ten years.

“Our findings confirm that pregnancy after breast cancer should not be discouraged, even for women with ER-positive cancer," said lead study author Dr Matteo Lambertini, medical oncologist and ESMO fellow at the Institut Jules Bordet in Brussels, Belgium. "However, when deciding how long to wait before becoming pregnant, patients and doctors should consider each woman's personal risk for recurrence, particularly for women who need adjuvant hormone therapy.”

This is the largest study to date to investigate the safety of pregnancy after breast cancer and the only to address this question specifically in women with ER-positive breast cancer, which is the most common type of breast cancer.

Among the 1,207 patients included in the study, 333 of the women became pregnant, and the average time from diagnosis to conception was 2.4 years.

Although there was limited data on breastfeeding in this study (64 patients, with 25 women who reported having breastfed their newborn), the results suggest that breastfeeding is feasible, even after breast surgery, the authors noted.

“These data provide reassurance to breast cancer survivors that having a baby after a breast cancer diagnosis may not increase the chance of their cancer coming back. For many young women around the world who want to grow and expand their families, it’s very comforting news,” said Professor Erica Mayer, ASCO Expert.

The study was presented earlier this month at the 2017 American Society of Clinical Oncology (ASCO) Annual Meeting, the largest oncology meeting in the world. The original abstract can be viewed here:

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