Knowledge Center

Breast cancer is a malignant tumor that develops in the breast tissue, usually in the glands that produce milk or the ducts that carry it. The tumor either invades other nearby tissue or spreads to other parts of the body. To date, breast cancer is the most common cancer in women and the leading cause of cancer death in women worldwide.

For the most part, the cause of breast cancer is still unknown. Contrary to popular belief, genetics are responsible for only a very small percentage of cases. Only 5%-10% of all breast cancer cases are related to the gene mutations BRCA1 and BRCA2, which scientists have identified as having a significant role in the development of the disease (1). In recent years, scientists are increasingly pointing out the relationships between genetics and the environment for possible solutions (2). One study has shown that the rates of breast cancer among descendants Japanese women who have immigrated to the United States were equal or higher than those of Western women within one or two generations (1). This study suggests that there might be a connection between a complete change in living conditions - including changes in exposure to air pollutants, drinking water, types of food and consumption habits - and morbidity.

The relation between breast cancer and exposure to chemicals is considered one of the leading areas of research nowadays, and scientists have already identified 216 chemicals that cause breast tumors in animals. 100 of them are part and parcel of our everyday life and can be found in smoked and grilled foods, traffic-related air pollution, coal fired power stations, and more (3).

In December 2011 the American Institute of Medicine (IOM) issued a report that identified steps associated with environmental factors that might reduce women's risk for breast cancer. The importance of this report lies in the fact that for the first time an authoritative medical group states a plausible link between pollutants and industrial chemicals with biological activity that suggests breast cancer risk.

Among the environmental factors that were reviewed the report singled out combined estrogen and progestin based hormone therapy, exposure to ionizing radiation, overweight postmenopausal women and alcohol consumption as evidence that was most consistent of a link to increased risk for developing breast cancer. The evidence regarding smoking are diverse: some important reviews found that smoking is causally related to breast cancer, but others concluded that the evidence is restricted.

The IOM statements also reports that greater physical activity is linked with a decrease risk for breast cancer. Exposure to hair dyes and non-ionizing radiation (from microwave, for example) failed to show greater risk for developing breast cancer.

The report states also that for secondhand smoke, working in nighttime shifts, and exposure to the chemicals benzene, ethylene oxide, or 1,3-butadiene the evidence is less persuasive but suggests a possible association with increased risk.

In light of these findings, the report recommends women to avoid exposure to unnecessary ionizing radiation, avoid combined estrogen and progestin based hormone therapy, avoid smoking, minimal alcohol consummation and increase physical activity (4).