Chemo During Pregnancy Doesn’t Harm Baby

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A German study suggests that chemotherapy during pregnancy doesn't have harmful effects on the baby. These results were presented at the 2010 San Antonio Breast Cancer Symposium (SABCS).

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.

Many doctors believe that chemotherapy can be given safely during pregnancy, but don't give chemotherapy during 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.

Some types of chemotherapy medicines are considered safer than others during pregnancy.

Anthracyline 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 260 women diagnosed with breast cancer while they were pregnant:

  • 142 women got chemotherapy during pregnancy; most of them got an anthracycline chemotherapy regimen
  • 118 women waited to get chemotherapy until after the baby was born; most of them got a taxane chemotherapy regimen

Most of the women were diagnosed with more aggressive types of breast cancer (grade 3, cancer in the lymph nodes), which is probably why chemotherapy was recommended.

On average, the women were diagnosed when they were 23 weeks pregnant (a normal pregnancy lasts about 40 weeks). The women who got chemotherapy during pregnancy were diagnosed earlier -- at about 20 weeks -- compared to the women who got chemotherapy after the baby was born -- about 28 weeks.

Half of the women had a Cesarean section (C-section) to deliver the baby; 29 women either had a spontaneous miscarriage or chose to terminate the pregnancy.

Comparing the outcomes of women who got chemotherapy during pregnancy to women who waited until after the baby was born:

  • the babies' birth weights were about the same
  • women who waited to get chemotherapy until after the baby was born were twice as likely to deliver prematurely (33%) compared to women who got chemotherapy during pregnancy (16.9%); this was probably because the women chose to deliver prematurely to start chemotherapy as soon as possible

There was no real difference in the risk of a baby having problems after delivery between the two groups of women, though a few more of the babies of the women who got chemotherapy during pregnancy had problems:

  • 12% of the babies born to women who got chemotherapy during pregnancy had some issues during the first 4 weeks of life: three babies had a congenital birth defect; four babies had infection concerns right after birth; two babies had low white blood cell count (neutropenia); and two babies had anemia (low red blood cell count)
  • 6.7% of the babies born to women who waited to get chemotherapy until after the baby was born had some issues during the first 4 weeks of life: one baby had a congenital birth defect, and one baby had low white blood cell count (neutropenia)

While this difference seems large, it was not statistically significant, which means that it could have been due to chance and not because of the difference in the timing of chemotherapy.

Survival without the cancer coming back (disease-free survival) and overall survival was the same for the two groups of women. Still, the women were followed for only about 2 years. Because the follow-up period was so 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.

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 can be surprisingly safe.
  • 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 Fertility, Pregnancy, and Adoption section.

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