Pregnancy-associated breast cancer: a review for the obstetrical care provider.

Breast cancer is uncommon in pregnancy, but obstetrical care providers should nevertheless be familiar with the presenting signs and symptoms. The incidence of breast cancer in pregnancy and the postpartum period ranges from 2.3 to 40 cases per 100 000 women. Over 90% of patients with breast cancer in pregnancy or during lactation present with a palpable mass, and most often (84%) these are self-reported by patients. Less frequently, breast cancer will present as breast erythema, breast swelling, bloody nipple discharge, or local or distant metastasis. The histology of tumours appears to be similar in women who are pregnant or recently delivered and in age-matched women who are not pregnant. However, the stage of disease at diagnosis is more advanced in women who are pregnant or recently delivered and consequently incurs a worst prognosis, likely due to a delay in diagnosis. Although the majority of palpable breast masses are benign, breast examinations should routinely be performed in pregnant women, and identified masses should be promptly evaluated.