After treatment of breast cancer to the satisfaction of her oncologist, should a woman who desire to get pregnant be discouraged from doing so? A very critical question considering the fact that there are close to half a million breast cancer survivors living in the US and are in the childbearing age.
For a very long time, counseling of women regarding pregnancy was dependent on the fact that estrogen increases during pregnancy and because estrogen has some effects on both estrogen receptor positive and estrogen receptor negative breast cancers, its probably better if women avoid pregnancy-unless of course another woman is carrying for them, a gestational carrier. This recommendation is not based on strong scientific evidence.
Safety of pregnancy after breast cancer treatment. All the published reports included a total of 1417 women who got pregnant after breast cancer treatment and 18059 who survived breast cancer and did not get pregnant. Women who got pregnant following breast cancer diagnosis had significantly better survival compared to women who did not get pregnant. In fact, those who got pregnant were more than 40% less likely to die because of breast cancer.
Important caveat to these studies is the healthy mother bias-the tendency of healthier women to desire and attempt pregnancy and the less healthy women to avoid pregnancy. This may inflate the safety of becoming pregnant after breast cancer treatment. Studies also largely did not address the chance for recurrence. Nevertheless, no study showed detrimental effect in breast cancer survivors who become pregnant. The largest of these studies published by The Danish Breast Cancer Cooperative Group was a population based study and included over 10,000 women who survived breast cancer and were under the age of 45. Three hundreds and sixty-seventy one women experienced 465 pregnancies and 236 deliveries. Women who got pregnant-full term or spontaneous miscarriage, were at least 30% less likely to die from breast cancer. Women with low risk breast cancers enjoyed 45% higher chance for survival after full term pregnancy than similar women who did not get pregnant.
How long should women wait after breast cancer treatment before attempting pregnancy? The majority of experts recommend waiting for about two years as the majority of recurrences takes place within this period. There are differences in recurrence pattern, however, between estrogen receptor negative and estrogen receptor positive tumors. Estrogen receptor negative tumors are more common in younger women and tend to recur earlier-within 2years after treatment. Recurrence of estrogen receptor positive cancers remain as high as 4–5% per year for about 15 years.
Pregnancy in BRCA1 and BRCA2 mutation carriers. In BRCA1 pregnancy does not seem to increase the risk of early onset breast cancer. In BRCA2 carriers, pregnancy may cause a borderline increase in risk of breast cancer before 50, especially when first pregnancy after age 40.
Breast feeding is recommended whenever possible in women treated for breast cancer, even if they are BRCA carriers and does not appear to impact breast cancer prognosis and may even be protective in some cases.
Contraception. If pregnancy is not desired as during breast cancer treatment and the follow up period after treatment non hormonal contraception is recommended such as IUD or barrier method e.g. condom. BRCA1 carriers may show an increased risk for early onset breast cancer if they use oral contraceptive pills before the age of 30 or for more than 5 years.
Young women diagnosed with breast cancer are commonly very concerned about their future fertility and safety of pregnancy after treatment. Proper counseling enables them to make appropriate decisions about future reproduction and fertility preservation. At the end of the day, most of the breast cancer battles will be won, some will be lost, pregnancy does not appear to contribute to that loss.