Breast cancer and pregnancy: Critical review of the effects of prior and subsequent pregnancy on the prognosis of young women with breast tumor

Pregnancy-associated breast cancer (PABC) is defined as breast malignancy diagnosed during pregnancy, within a year to delivery, or at any time during lactation. Those tumors present a challenging clinical situation, and recommendations for staging workup and local and systemic therapy require the consideration of the welfare of both the mother and her fetus. Whereas patients with PABC often present with poorer survival rates as compared with affected young nonpregnant individuals, there is a debate whether pregnancy per se is a poor prognostic factor or mediates dismal outcome due to association with advanced stage at diagnosis and frequent treatment delays. Similar dismal tumors may occur also in young women susceptible to develop breast tumors in association with ovarian stimulation by fertility drugs, suggesting a common mechanism for breast cancer development in a subgroup of susceptible young women exposed to high levels of endogenous estrogens. The effect of subsequent pregnancy on the outcome of a premenopausal woman with a history of breast cancer has been suggested to be "protective" in several series mostly in otherwise "healthy mothers" with early breast tumors. At the current time, no solid conclusions can be made with regard to safety in estrogen receptor (ER) -positive disease, especially node-positive disease. Breast cancer is the most common female malignancy worldwide, expected to affect 207,090 women in the United States in the year 2010 with a median age at diagnosis of 61 years [1]. Although disease occurrence is linked to female sex hormones and reproductive factors [2-5], most patients are diagnosed during their postmenopausal years when potent estrogens are no longer produced by the ovaries. Only 1.9% of tumors occur in women aged 20-34 years, and 10.5% in those aged 35-44 years. Molecular profiling of breast tumors suggests that several disease subtypes exist, each with distinct pathogenesis mechanisms, biological phenotypes, and clinical outcomes.