Pregnancy Does Not Boost Breast Cancer Recurrence

Nov.? 2, 2010 (San Diego) -- Despite fears to the contrary, women who get pregnant after receiving radiation treatment for early breast cancer are not at increased risk of having their cancer come back, a new study suggests.

"In fact, the risk of recurrence was lower among women who became pregnant," says researcher Ahlam Aljizani, MD, of the Ottawa Regional Cancer Center in Canada.

In the study of 201 women with early breast cancer, 28.2% of the 39 patients who later became pregnant had a recurrence vs. 55.6% of those who did not get pregnant.

Pregnancy and Risk of Breast Cancer Recurrence

Although several studies have suggested a neutral or even beneficial effect of pregnancy on recurrence rates in women who receive radiation, there have been fears that the increased levels of hormones during pregnancy might stimulate tumor growth, Phillip Devlin, MD, a radiation oncologist at Harvard Medical School, tells WebMD.

"This study does not support those fears," says Devlin, who was not involved with the work.

The findings were presented here at the 52nd Annual Meeting of the American Society for Radiation Oncology.

Timing of Pregnancy

For the study, the researchers reviewed the medical records of women treated for early breast cancer between 1961 and 2005 at their institution. The average age of the women was about 28, and ranged from 19 to 30 years.

The women were treated with either breast-conserving surgery followed by radiation with or without chemotherapy and/or hormone therapy as needed or mastectomy. They were followed for an average of about 11 years, during which time about half of the patients had a recurrence.

Among the findings:

• Among women who became pregnant, the risk of recurrence was unaffected by the time of pregnancy, with those who conceived in the 12 months after diagnosis no more likely to have their cancer come back than women who got pregnant in later years.
• The choice of treatment only affected recurrence rates among women who did not get pregnant, Aljizani tells WebMD. Among these women, those who got breast-conserving surgery and radiation were 54% less likely to have their cancer come back, compared with those who had a mastectomy.

The analysis took into account other factors that affect the risk of recurrence, including whether the cancer had spread to the lymph nodes and choice of treatment, she says.

Study Limitations

A drawback of the study is that the researchers looked back at the records of the women rather than following them over time, Devlin says.

"This means there are various biases. For example, it could be that women who didn't get pregnant were sicker and therefore at greater risk of recurrence," he says.

That said, it would be very difficult, if not impossible, to do a more robust study in which women are followed over time, Devlin says. "You can't predict who will get pregnant and who won't," he says.