Summer 2007 Volume 103 Issue 3 : letters
Re: "Out in the Open," Spring 2007
The article "Out in the Open: Environmental Risks and Breast Cancer” (Spring 2007) may leave readers with the mistaken impression that environmental risks have contributed to recent increases in the incidence of breast cancer. While some groups like Breast Cancer Action do push this view, it is based more on chemical-phobia than sound epidemiology.
Breast cancer is on the rise because we are looking for it. Over the last two decades, the proportion of women aged 40 years and older who have been screened has more than doubled. American women are also screened much more aggressively than women in Europe. Mammography detects early-stage tumors that would later develop into late-stage cancer. It also detects small tumors that would never have become clinically apparent if left untreated. Notably, increases in the incidence of early-stage tumors account for almost all of the increase in total breast cancer incidence.
Other factors that may contribute to increases in breast cancer incidence include reductions in heart disease mortality (the longer you live, the more likely you are to develop and test positive for cancer), changes in childbearing patterns, obesity and lack of exercise, and use of hormone replacement therapy.
David Howard ’94
Decatur, Georgia
Indeed the message of our work is that there is substantial and increasingly strong scientific evidence that environmental chemicals may be contributing to the current high rates of breast cancer. Improvements in detection have certainly led to higher rates of diagnosis and reporting, and the many factors that Professor Howard [associate professor of health policy and management, Emory University] lists are also important. Yet they are not sufficient to explain the trends in cancer rates observed over the past several decades.
Increasingly sophisticated epidemiological data, supported by toxicological and cellular biology studies, support the concern that environmental chemicals may alter the risk for breast cancer later in life, especially when developing girls are exposed in utero, during childhood, and/or during adolescence. I believe these data warrant serious and thoughtful discussion, not dismissal.
Professor Janet Gray,
Project Director for the
Environmental Risks and Breast Cancer CD Project