SAN ANTONIO — Survival outcomes in women with pregnancy-associated breast cancer were significantly worse than in nonpregnant controls matched for age and tumor stage in a relatively large single-center study.
This finding is at odds with most prior series, which have found no difference in 5-year survival depending upon whether a breast cancer patient was pregnant, study investigator Dr. Rajesh Sehgal said at the San Antonio Breast Cancer Symposium.
“We don't know why our results were different. We could not explain it on any basis,” he said in an interview.
Breast cancer is the most frequently diagnosed malignancy in pregnancy, with an incidence of roughly three cases per 10,000 live births.
Dr. Sehgal presented a retrospective study involving 40 women with pregnancy-associated breast cancer (defined as breast cancer diagnosed during pregnancy, within 1 year of delivery, or at any time during lactation) and 40 matched nonpregnant controls, all treated at University of Pittsburgh Medical Center.
Median overall survival was 4.9 years in the pregnancy-associated breast cancer group, significantly less than the 6.0 years in controls. Median disease-free survival was 2.7 years in women with pregnancy-associated breast cancer, compared with 5.1 years in controls. The most common site of relapse in the pregnancy-associated breast cancer group was bone. In controls, recurrences were most commonly local.
Pregnancy remained an independent predictor of worse outcomes in breast cancer patients after adjusting for key variables including hormone receptor status, family history, tumor stage, human epidermal growth factor receptor 2 (HER2) status, and the use of radiotherapy and/or chemotherapy.
None of the studies reported to date is large enough to be definitive, and a national registry is warranted, Dr. Sehgal said.