Pregnancy has no impact on breast cancer, but can delay diagnosis and treatment

A new study finds women who develop breast cancer while pregnant or soon afterwards do not experience any differences in disease severity or likelihood of survival compared to other women with breast cancer.

The study is published in the March 15, 2009 issue of CANCER , a peer-reviewed journal of the American Cancer Society.

So-called pregnancy-associated breast cancers (PABC), defined as breast cancer that develops either during or within one year following pregnancy, is relatively rare and presents a dilemma for clinicians. An estimated 0.2 to 3.8 percent of pregnancies are complicated by breast cancer, and approximately 10 percent of breast cancer patients under age 40 develop the disease during pregnancy. But as age at the time of pregnancy continues to increase, the incidence of PABC can be expected to increase.

Previous research has suggested that pregnancy is associated with poorer outcomes among women with breast cancer. To clarify the issue, Drs. George Perkins, Beth Beadle and colleagues at The University of Texas M.D. Anderson Cancer Center analyzed data from 668 breast cancers in 652 patients aged 35 years or younger. Among that group, 104 breast cancers (15.6 percent) were pregnancy-associated: 51 cancers developed during pregnancy and 53 developed within one year following pregnancy.

There were no statistically significant differences in 10-year rates of cancer recurrence, cancer spread, or survival among patients with PABC compared with other women who developed breast cancer. However, pregnancy contributed to a delay in breast cancer diagnosis, evaluation and treatment. The researchers also found treatment during pregnancy improved survival compared with delaying treatment until after delivery among those who with PABC.

"Primary care and reproductive physicians should be aggressive in the work-up of breast symptoms in the pregnant population to expedite diagnosis and allow multidisciplinary treatment," the authors write. "Balancing the health of mother and child is… paramount; new evidence suggests that both can be prioritized and successful outcomes managed for both," they added.