Bilateral oophorectomy in a pregnant woman: hormonal profile from late gestation to post-partum: Case report

Systemic Treatments in Pregnancy-Associated Breast Cancer

Available data on systemic treatments in pregnancy-associated breast cancer (PABC) is reviewed in this section. These treatments include chemotherapy, endocrine therapy (ET), small molecule inhibitors, monoclonal antibodies against human epidermal growth factor receptor 2 (EGFR-2) also known as HER2; and human epidermal growth factor receptor 3 (EGFR-3), also known as HER3.In local disease, systemic treatment can be delivered as neoadjuvant (before surgery) or adjuvant (after surgery) treatment. In metastatic disease, systemic therapy is the main modality of treatment.Approach to PABC is based on available data in the general population, limited only by safety issues for use of medications during gestation and lactation. Therefore, treatments are similar to non-PABC patients while trying to minimize the risk to the fetus. Available data on different chemotherapies, anti-HER2 monoclonal antibodies, ET and small molecule inhibitors are discussed in detail.

Systemic stromal effects of estrogen promote the growth of estrogen receptor-negative cancers

Numerous hormonal factors contribute to the lifetime risk of breast cancer development. These include inherited genetic mutations, age of menarche, age of menopause, and parity. Inexplicably, there is evidence indicating that ovariectomy prevents the formation of both estrogen receptor (ER)-positive and ER-negative breast cancers, suggesting that ER-negative breast cancers are dependent on ovarian hormones for their formation. To examine the mechanism(s) by which this may be occurring, we investigated the hypothesis that steroid hormones promote the outgrowth of ER-negative cancers by influencing host cell types distinct from the mammary epithelial cells. We used a novel xenograft mouse model of parturition-induced breast carcinoma formation, in which the tumors that arise following pregnancy lack the expression of nuclear hormone receptors, thereby recapitulating many clinical cases of this disease. Despite lacking ER expression, the tumors arising following pregnancy in this model require circulating estrogens for their formation. Moreover, increasing the levels of circulating estrogens sufficed to promote the formation and progression of ER-negative cancers, which was accompanied by a systemic increase in host angiogenesis and was attendant with the recruitment of bone marrow-derived stromal cells. Furthermore, bone marrow cells from estrogen-treated mice were sufficient to promote tumor growth. These results reveal a novel mechanism by which estrogens promote the growth of ER-negative cancers.