Researchers at the University of Texas M.D. Anderson Cancer Center in Houston found a statistically significant five-year disease-free survival rate of 73.94 percent in pregnant women, compared to 55.75 percent in the non-pregnant patients.
"From this data set and our study, we are not sure why our pregnant breast cancer patients had better outcomes than those who were not," first author Dr. Jennifer Litton says in a statement. "Is there something biological in the milieu of pregnancy that changes the response to chemotherapy? Or were these patients treated more aggressively?"
Past registry studies, says Litton, showed breast cancer patients treated while pregnant had a worse outcome.
"However, in the past, these patients weren't always treated consistently with standard of care chemotherapy and often delayed their therapy until after delivery, she says.
Litton and colleagues compared 75 women treated for breast cancer while pregnant and 150 non-pregnant breast cancer patients matched by stage, age and year of diagnosis. All were patients at M.D. Anderson from 1989 to 2008.
The findings are being presented at the 2010 Breast Cancer Symposium in Washington.