Overview Documents

Review of the Etiology of Breast Cancer with
Special Attention to the Potential Role of Organochlorines


Abstract

Breast cancer is the most frequently diagnosed cancer among Canadian women, accounting for about 30% of all new cancer cases each year. Although, the incidence of breast cancer has been increasing slightly over the past 50 years, the cause of this increase is unknown. Risk factors for breast cancer can be classified into four broad categories: genetic/familial, reproductive/hormonal, lifestyle, and environmental. Established risk factors for breast cancer include older age, later age at first full-term pregnancy, no full-term pregnancies, postmenopausal obesity, and genetic factors. However, these known risk factors cannot account for the majority of documented cases of breast cancer. It has been suggested that exposure to some environmental chemicals such as organochlorines may play a causal role in the etiology of breast cancer through estrogen-related pathways. Although, the relationship between organochlorines and breast cancer risk has been studied extensively in the past decade, currently available data linking exposure to these environmental estrogens and breast cancer are equivocal. At this point, there is no strong evidence to support a causal role of organochlorines as a group in the etiology of human breast cancer. However, specific chemicals within this group, such as Mirex and PCB congeners, may be associated with increased risk.

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