Breast cancer in pregnancy and lactation.

Although breast cancer is the most common malignancy in pregnancy, its overall incidence remains low. It appears that pregnancy and breast cancer are merely coincidental and that pregnancy does not directly contribute to the development or accelerated progression of breast cancer. The majority of studies have documented a significant delay in diagnosis secondary to physiologic changes of the breast during pregnancy and have reasoned that this is the likely explanation for the advanced stage of disease upon initial presentation. Although pregnant patients present at a later stage of breast cancer, survival stage for stage is the same when pregnant patients are compared with young nonpregnant patients with breast cancer. A suspicious breast mass in a pregnant patient should be biopsied and appropriately treated, without need for extensive preoperative staging. Therapeutic abortion should be performed only on an individual basis, namely in patients in whom necessary radiation or chemotherapy would be detrimental to the developing fetus and in whom a significant delay of this treatment would be harmful. In patients with early-stage disease, it is recommended to wait 2 years after treatment of breast cancer for subsequent pregnancy; however, in women with advanced disease, subsequent pregnancy should be discouraged.