Pregnancy around the time of a breast cancer diagnosis does not appear to have a negative impact on survival, according to Canadian researchers.
As Dr. Steven A. Narod told Reuters Health by email, "We found that very young women have a generally unfavorable course of breast cancer, compared to older women, but the risk was not exacerbated by pregnancy."
As reported March 9 online in JAMA Oncology, Dr. Narod of Women’s College Hospital, Toronto and colleagues studied more than 7,500 such women diagnosed with breast cancer between ages 20 and 45.
Any pregnancy within five years before or after the diagnosis was included. Women were grouped as having no pregnancy (the referent), pregnancy before breast cancer, pregnancy-associated breast cancer, and pregnancy following breast cancer.
Five-year actuarial survival rates were 87.5% in those with no pregnancy, 85.3% in women with pregnancy before breast cancer, 82.1% in women with pregnancy-associated breast cancer, and 96.7% in women who became pregnant at least six months after their diagnosis.
"Surprisingly," added Dr. Narod, "we found that having a baby after breast cancer seemed to indicate that the chance of recurrence was lower than expected but the biologic basis for this favorable outcome is unclear and the finding needs to be confirmed."
It’s possible this might be due "to some degree of the so-called healthy mother effect, in which women who conceive are most likely to be a self-selected group of healthy women with better prognoses," he and his colleagues suggest.
The age-adjusted hazard ratio of all-cause mortality for women with pregnancy-associated breast cancer versus those without was 1.18. The difference was not significant. This was also the case in multivariable analysis and in models allowing for use of radiotherapy and chemotherapy or both.
Summing up, Dr. Narod said, "Young women who have breast cancer when pregnant face many challenges and it is important that they be given correct and up to date information. We no longer believe that terminating a pregnancy for a breast cancer patient is in the best interest of the mother and many effective treatment options are now available.