Breast cancer and pregnancy

Breast cancer is the most commonly occurring malignancy among women of reproductive age and the second most common pregnancy-associated cancer, after cervical cancer [1,2]. Pregnancy-associated breast cancer (PABC) is defined as breast cancer diagnosed during pregnancy or within one year postpartum and it is estimated to account for up to 3% of all breast cancers. The prevalence of PABC is between 1 in 3,000 and 1 in 10,000 pregnancies. A high index of suspicion is required when evaluating a breast mass among pregnant and lactating women because of the substantial physiological changes of the female body during pregnancy. When a new breast mass is suspected, diagnostic evaluation must begin promptly. Although mammography is the imaging of choice among nonpregnant women with a breast mass, its sensitivity declines among pregnant and lactating women due to the glandularity and the water content of the breast [1]. In one study, the false-negative mammography rate was significantly higher among pregnant women than among nonpregnant women (14% vs. 6%, respectively; P < 0.0001) [3]. Ultrasound is the modality of choice when PABC is suspected. It has been reported to distinguish solid from cystic lesions in 97% of cases [4], and with 100% sensitivity in a few studies [1,5,6]. There are insufficient evidence-based data regarding the efficacy of magnetic resonance imaging (MRI) and the safety of gadolinium during pregnancy. Thus, the international recommendations from an expert meeting summarized by Loibl et al. recommended against it [7].