Postpartum breast cancer: mechanisms underlying its worse prognosis, treatment implications, and fertility preservation

Abstract

Breast cancers that occur in young women up to 5 to 10 years' postpartum are associated with an increased risk for metastasis and death compared with breast cancers diagnosed in young, premenopausal women during or outside pregnancy. Given the trend to delay childbearing, this frequency is expected to increase. The (immuno)biology of postpartum breast cancer is poorly understood and, hence, it is unknown why postpartum breast cancer has an enhanced risk for metastasis or how it should be effectively targeted for improved survival. The poorer prognosis of women diagnosed within 10 years of a completed pregnancy is most often contributed to the effects of mammary gland involution. We will discuss the most recent data and mechanistic insights of the most important processes associated with involution and their role in the adverse effects of a postpartum diagnosis. We will also look into the effect of lactation on breast cancer outcome after diagnosis. In addition, we will discuss the available treatment strategies that are currently being used to treat postpartum breast cancer, keeping in mind the importance of fertility preservation in this group of young women. These additional insights might offer potential therapeutic options for the improved treatment of women with this specific condition.

The Risk Factors, Incidence and Prognosis of Postpartum Breast Cancer: A Nationwide Study by the SMARTSHIP Group

“…However, even after adjusting for age at diagnosis, prognosis was significantly poor (20) [20]. Several previous studies of young breast cancer patients have shown that breast cancer within 5-10 years of delivery has a worse prognosis than that of breast cancer in nulliparous women (46)(47)(48). Many preclinical studies have suggested that it this related to a developmental tissue remodeling process of mammary gland involution (9-11, 13, 23, 49), which may result in distinct gene expression profiles.…”

Abscess-like postpartum metaplastic breast carcinoma in breastfeeding woman: a case report

“…6 Therefore, age at diagnosis, parity status and breastfeeding history are important risk factors for breast cancer. 7,8 PPBC is associated with worse survival rates presenting two-to threefold increased risk of death in both ER+ and ER-disease. 6,9,10 Interestingly, studies have shown that diagnosis during pregnancy is not associated with poorer outcomes.…”

“…In both murine and human mammary glands, postpartum involution begins with controlled apoptosis of mammary epithelial cells. 7 In this process, a minority of mammary epithelial cells survives the death and resistance to cell deaths can probably play an important role in tumor initiation, as it results in the propagation of potentially harmful mutations that allow unregulated growth and division. 13 In this case, the patient PPBC was diagnosed as metaplastic breast carcinoma (MBC) of high histological grade which is a subtype of triple-negative breast cancer and accounts for approximately 1% of all breast cancers.…”

Clinical characteristics and pathologic complete response (pCR) rate after neoadjuvant chemotherapy in postpartum women with breast cancer

“…The World Health Organization recommends 150 min of moderate-intensity physical activity per week for pregnant and postpartum women to help further heal and improve women's mental health (Bull et al 2020 ; Neil-Sztramko et al 2014 ). Recent studies have also identified potential targets for treating PPBC, including pathways related to lymphangiogenesis and immunomodulation, offering hope for treating these patients (Lefrère et al 2021 ).…”