A review of the experiences of more than 400 women who received chemotherapy to treat breast cancer while they were pregnant suggests that the treatment doesn’t harm the baby.
The study was published online on Aug. 16, 2012 by The Lancet Oncology. Read the abstract of “Treatment of breast cancer during pregnancy: an observational study.”
Breast cancer is sometimes diagnosed when a woman is pregnant. Depending on the characteristics of the cancer, chemotherapy may be recommended. Doctors don’t agree on the best time to start chemotherapy when a pregnant woman is diagnosed with breast cancer. It’s also not clear which chemotherapy medicines are best for pregnant women and if the doses should be different for them.
Most doctors agree that chemotherapy should be given only after the first trimester (the first 12 to 14 weeks). This is because the baby’s organs are developing rapidly during the first trimester. Doctors also don’t give chemotherapy near the delivery date. In most cases, the last dose is given about 8 weeks before the delivery date (32 to 33 weeks into the pregnancy). This is because chemotherapy can lower white blood cell counts (neutropenia), which can increase the risk of infection in the mother and the baby around the time of delivery.
Anthracycline chemotherapy regimens are more commonly used when chemotherapy is needed during pregnancy. Adriamycin (chemical name: doxorubicin) and Ellence (chemical name: epirubicin) are anthracyclines; they’re often given in combination with Cytoxan (chemical name: cyclophosphamide).
Taxane chemotherapy regimens aren’t commonly used during pregnancy. Taxol (chemical name: paclitaxel), Abraxane (chemical name: albumin-bound or nab-paclitaxel), and Taxotere (chemical name: docetaxel) are all taxane chemotherapy medicines.
This study looked at the experiences of 447 women from seven European countries who were diagnosed with breast cancer when they were pregnant:
- 413 of the women were diagnosed with early-stage breast cancer
- the women’s ages ranged from 22 to 51
- on average, the women were diagnosed when they were about 24 weeks pregnant (a normal pregnancy lasts about 40 weeks)
Of the 413 women diagnosed with early-stage disease, 197 (48%) got chemotherapy while pregnant:
- 178 women got an anthracycline regimen
- 15 women got Cytoxan, methotrexate, and fluorouracil
- 14 women got a taxane
None of the women got chemotherapy during the first trimester.
The researchers compared the outcomes of babies whose mothers had chemotherapy while they were in the womb to babies whose mothers waited to have chemotherapy until after they gave birth:
- there was no difference in birth defects
- babies exposed to chemotherapy had a slightly lower birth weight
- 15% of babies exposed to chemotherapy had complications in the first four weeks of life compared to 4% of babies who weren’t exposed to chemotherapy
While this difference in complications seems large, it wasn’t statistically significant, which means that it could have been due to chance and not because of the difference in the timing of the chemotherapy.
Complications were more common in babies who were born prematurely (before the 37th week of pregnancy) whether or not they were exposed to chemotherapy.
Two of the babies died. Both the mothers had received chemotherapy while pregnant and the babies were born prematurely. Still, the researchers believe the deaths weren’t related to the mothers receiving chemotherapy.
Half of the women diagnosed with breast cancer delivered early – 23% delivered before the 35th week. On average, about 10% to 15% of babies are born prematurely around the world. Women who waited to have chemotherapy until after they delivered were slightly more likely to deliver early. Still, this difference also wasn’t statistically significant.
The length of time the mothers lived without the cancer coming back (disease-free survival) was the same for mothers who got chemotherapy during pregnancy and mothers who waited until after delivering to start chemotherapy. But the women have been followed for only about 4 years. Because this follow-up period is short, we can’t make any conclusions about the possible longer-term risks for moms and babies from giving chemotherapy during pregnancy or after delivery. Other studies with longer follow-up suggest that chemotherapy during pregnancy – after the first trimester – poses no special risks for the baby.
The researchers pointed out that premature birth was strongly linked to complications in the first few weeks of life for the babies, whether or not their mothers had chemotherapy during pregnancy. Carrying a baby to full-term seems to be the most important factor affecting the health of the baby in women diagnosed with breast cancer while pregnant.
If you've been diagnosed with breast cancer and are pregnant, you and your doctor will work very carefully to develop a treatment plan that makes the most sense for you and your unique situation. Chemotherapy may or may not be a part of your treatment plan. When thinking about your situation and your options, keep these things in mind:
- A barrier between the mother's body and the baby's body blocks any cancer cells from going into the baby or its blood supply, so you can be confident that your baby won't get cancer from you.
- Your decision to delay treatment or consider terminating the pregnancy will depend on the characteristics of the cancer and how urgently your doctor thinks you need to start treatment.
- This study and several others have shown that chemotherapy given during the second or third trimesters appears safe for both the mother and the baby.
- If hormonal therapy is recommended, you usually won't start that until after your baby is born.
- Breast cancer treatment can affect your ability to get pregnant again in the future.
You can learn more about breast cancer treatment during pregnancy and treatment-related fertility issues in the Breastcancer.org Fertility and Pregnancy Issues During and After Breast Cancer section.
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