Chemotherapy does not need to be delayed in women whose breast cancers are discovered during pregnancy, German researchers reported at the CTRC-AACR San Antonio Breast Cancer Symposium.
A registry review of 260 patients showed that chemotherapy had no major effect on maternal or fetal outcomes, including reduced birth weight or congenital malformations, said lead researcher, Sibylle Loibl, MD, of the German Breast Group.
But nearly twice as many women who didn't get chemotherapy had premature deliveries: 33.0% gave birth before Week 35 versus 16.9% of women who took the drugs. Dr. Loibl speculated that it's likely that physicians induced earlier deliveries among women who weren't on chemotherapy so they would be able to start on the drugs as soon as possible.
About 2% of all breast cancers are diagnosed during pregnancy, she said. The number may rise, however, as more women delay pregnancy until later in life.
“A lot of physicians still advise pregnant patients to delay treatment. That's not the right thing to do. Patients should be treated as closely as possible to standard recommendations for non-pregnant women,” Dr. Loibl said.
The study included 142 women who received chemotherapy during pregnancy, 110 (77%) of whom were given an anthracycline-based regimen, typically doxorubicin or epirubicin plus cyclophosphamide. Only six received a taxane.
In contrast, the majority of the 118 women who were given chemotherapy after pregnancy received a taxane.
The women, age 23 to 47, were diagnosed with breast cancer at a median gestational age of 23 weeks. About 23% of all patients were diagnosed during the first trimester, 42% during the second trimester, and 36% during the third trimester.
The women who received chemotherapy during pregnancy were diagnosed earlier, at a median gestational age of 20 weeks versus 28 weeks for those who waited, but the difference was not statistically significant.
A total of 48% of patients had a cesarean section, and 10% had an abortion or miscarriage.
No Effect on Birth Weight
The mean birth weight of infants exposed to intrauterine chemotherapy was 2,810 g (about 6.2 lbs) vs 2,730 g (about 6.02 lbs) for those not exposed, a nonsignificant difference.
A total of 12% of babies exposed to chemotherapy during pregnancy had an adverse event, typically a congenital malformation, in the first four weeks of life vs 6.7% of babies who were not on chemotherapy, but the difference was not statistically different.
Other adverse events among babies exposed to intrauterine chemotherapy were four cases of infection, two of neutropenia, two of anemia, one newborn small for gestational age, and one case of jaundice.
Among babies born to women who did not receive chemotherapy, there was one case of impaired liver function, one case of hypoglycemia, and one case of jaundice.
The two groups were not directly comparable because the women had different stages of breast cancer and received different drugs. Still, the health of the newborns was similar in both groups, Dr. Loibl reported.
Maternal outcomes were also similar, with women who took chemotherapy during pregnancy and those who waited having similar disease-free survival and overall survival rates.
Still, the researchers plan to compare all their outcomes with those of age-matched breast cancer patients who are not pregnant, as the median disease-free survival time of 28.7 months among the total cohort of pregnant women seems low, she said.
During the question-and-answer period, Steven E. Vogl, MD, a clinician from the Bronx, NY, commented that that he is reluctant to draw any conclusions until the children are followed for five or more years—”I, at least, am worried about exposing developing fetuses to anthracyclines and taxanes,” he said.
Dr. Loibl replied that there does not seem to be more adverse outcomes among those children followed for five years or more in the registry, but that they are continuing to monitor the children.
Steven J. Isakoff, MD, PhD, Assistant in Medicine at Massachusetts General Hospital Cancer Center, said that the findings are reassuring, supporting the practice of starting chemotherapy during pregnancy.
That said, precautions need to be taken, he said. At his institution, the last dose of chemotherapy is given by Week 32 or 33.
“That way, the white blood count will go up by the time of delivery. You want to avoid women being neutropenic at the time of delivery, as that increases the risk of infection to mother and baby.”
Edith A. Perez, MD, Director of the Breast Cancer Program and Professor of Medicine in the Division of Hematology/Oncology at the Mayo Clinic in Jacksonville, FL, cautioned that drugs such as methotrexate and gemcitabine should be avoided, particularly in the first trimester, as they affect cell division, posing a danger to new organs being formed in the fetus.
Drugs whose mechanisms involve cell death rather than interrupting cell division or cell growth are preferred in pregnancy, especially in the first trimester, she said.
Dr. Isakoff added that the low disease-free survival rate highlights “the general high-risk nature of this population of women.”