"Pregnancy-associated breast cancer" means the cancer is diagnosed while a woman is pregnant or during the year after pregnancy. A study shows that women younger than 35 diagnosed with pregnancy-associated breast cancer had the same long-term outcomes as women who weren't pregnant when diagnosed, though the pregnant women were more likely to be diagnosed with later-stage cancer.
Pregnancy-associated breast cancer doesn't happen very often. Still, as more women wait to have children, it's likely the risk of pregnancy-associated breast cancer will go up. The levels of the hormones estrogen and progesterone change during pregnancy and these hormones can help breast cancers develop and grow. So doctors wondered if breast cancers that develop during and right after pregnancy could have a worse prognosis.
The researchers looked at the records of 652 women, all younger than 35, treated for breast cancer. About 100 of the women were diagnosed with pregnancy-associated breast cancer -- 51 during pregnancy and 53 in the year after delivery. The researchers compared the 10-year outcomes of the women diagnosed with pregnancy-associated breast cancer to the 10-year outcomes of the women who weren't pregnant when diagnosed.
Breast cancer came back in the same area where it was first diagnosed (locoregional recurrence) in:
- 23.4% of the women diagnosed with pregnancy-associated breast cancer
- 19.2% of the women who weren't pregnant when diagnosed
This difference wasn't significant, which means it could have been due to chance.
Breast cancer came back some other place in the body, not the breast area (distant metastasis), in:
- 45.1% of the women diagnosed with pregnancy-associated breast cancer
- 38.9% of the women who weren't pregnant when diagnosed
This difference also wasn't significant, which means that it also could have been due to chance.
There was no difference in 10-year survival rates between the two groups of women:
- 64.6% of the women diagnosed with pregnancy-associated breast cancer were survivors
- 64.8% of the women who weren't pregnant when diagnosed were survivors
This difference also wasn't significant, which means that it could have been due to chance.
Still, the women diagnosed with pregnancy-associated breast cancer were more likely to have later-stage breast cancer compared to the other women. This may be because pregnancy may make it harder to detect breast cancer symptoms. Pregnancy also may cause women to wait to get a mammogram.
Some of the women diagnosed with breast cancer while pregnant started treatment before the baby was born. Other women waited to start treatment until after the baby was born. In this study, 10-year survival rates were better among women who started treatment while pregnant (78.7%), compared to survival rates among women who waited until after they gave birth to start treatment (44.7%).
If you've been diagnosed with breast cancer while pregnant or in the year after you gave birth, the results of this study are reassuring. If you're diagnosed while pregnant, you might want to wait and start treatment after you have your baby. This is understandable. Still, this study suggests that starting treatment while you're pregnant may make more sense. In 2006, the National Comprehensive Cancer Network created Guidelines for Treating Early-Stage Breast Cancer During Pregnancy. Talk to your doctor about these guidelines and the treatment options that are best for your unique situation. Together you'll develop treatment approach that's best for both you and your baby.