Breast cancer during pregnancy is rare: it accounts for only 0.4% of all cases diagnosed in women ages 16 to 49 years, with most diagnosed at age 40 years or younger. As routine screening mammography during pregnancy is not recommended, most diagnoses are by self-palpation.

During pregnancy, an increase in breast volume and density can delay diagnosis of a breast or axillary mass, leading to more locally advanced disease. Of the breast masses identified during pregnancy, however, 80% are benign.

Women with breast cancer during pregnancy are more likely than nonpregnant women to have grade 3, lymph node positive, estrogen and/or progesterone receptor triple-negative tumors. Incidence of breast cancer during pregnancy or lactation is increasing, in part due to older ages of childbearing women.

Survival outcomes are not improved if pregnancy is terminated after a diagnosis of breast cancer, except for women who need immediate treatment for advanced disease who have a poor prognosis early in the first trimester.

For these reasons, to “deliver the safest and best treatment plan to both the mother and developing fetus,” all aspects of care must be individualized, Carey K. Anders, MD, of the department of medicine, division of hematology-oncology at the Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, and colleagues reported in The Oncologist.

This requires multidisciplinary oncology management, with close involvement of obstetricians.

Following a targeted literature search on caring for women with breast cancer during pregnancy, the University of North Carolina multidisciplinary team — medical oncology, radiation oncology, surgical oncology, and pharmacology — compiled a comprehensive review to “provide evidence-based, practical guidance to the optimal approach and treatment of patients diagnosed with breast cancer during pregnancy.”

Key to developing a successful plan is tailoring treatment for each patient, considering “the timing of the pregnancy and the stage and subtype of the breast cancer,” they wrote.