Women with Primary Breast Cancer Diagnosed During Pregnancy Have Overall Survival Similar to Nonpregnant Patients 

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Results from an international collaborative study showed that women with primary breast cancer diagnosed during pregnancy had overall survival similar to nonpregnant patients. Reporting their findings in the Journal of Clinical Oncology, the authors concluded: “This information is important when patients are counseled and supports the option to start treatment with continuation of pregnancy.”

In a comparison of 311 women with breast cancer diagnosed during pregnancy and 865 women who were not pregnant, the hazard ratio of pregnancy was 1.19 (95% confidence interval [CI], 0.73–1.93; P = .51) for overall survival. Cox regression estimated that the 5-year overall survival rate would have increased from 78% to 81% if these patients had not been pregnant. 

For disease-free survival, the hazard ratio of pregnancy was 1.34 (95% CI = 0.93–1.91; P = .14) and Cox regression estimated that the 5-year disease-free survival rate would have increased from 65% to 71% if these patients had not been pregnant. “Regarding the [disease-free survival] analysis, the observed [hazard ratio] of 1.34 suggests better outcome for the nonpregnant group; however, the CI shows that any distinct effect of pregnancy cannot be concluded,” the investigators stated.

The age limit was 45 years, with a median age of 33 years for pregnant and 41 years for nonpregnant patients. Women with in situ or primary metastatic disease and those relapsing during pregnancy were excluded from the analyses, as were women who became pregnant during treatment or received their diagnosis postpartum. Analysis adjusted for age, stage, grade, hormone receptor status, human epidermal growth factor receptor 2 status, histology, type of chemotherapy, use of trastuzumab (Herceptin) radiotherapy, and hormone therapy.

Median follow-up was 61 months. “During follow-up, 42 pregnant patients (14%) and 103 nonpregnant patients (12%) died,” the researchers reported.

Maternal and Fetal Safety

Observations from this and other studies, “suggest that chemotherapy during pregnancy can be administered as it is in nonpregnant women (with chemotherapy dosing based on body surface area), despite the altered pharmacokinetics during pregnancy,” the authors noted. 

“Apart from maternal safety, fetal safety is also considered when patients are counseled. Chemotherapy exposure during the second and third trimesters of pregnancy did not impair neonatal outcome,” the researchers added.

“Taken together, the available data confirm maternal and fetal safety when breast cancer is treated during pregnancy,” the investigators concluded. “Standard treatment during pregnancy, including chemotherapy, adds to an optimal maternal outcome. This outcome now seems to be comparable to that of nonpregnant patients. In addition, the administration of chemotherapy during pregnancy contributes to fewer preterm deliveries and thus also to improved fetal outcome.”

“This study provides additional comfort for women and physicians who must care for the pregnant patient with breast cancer,” according to an editorial that accompanied the article. “The cancer can be treated, the pregnancy can be maintained, labor and delivery can be successful, and the outcome for mother and neonate can be expected to be favorable.” ■

Amant F, et al: J Clin Oncol 31:2532-2539, 2013.
Theriault RL, Litton JK: J Clin Oncol 31:2521-2522, 2013.