Breast cancer and environmental risks: where is the link?

* Breast cancer is the leading cause of cancer morbidity and mortality in women.

* In the United States, between 1994 and 1998, female invasive breast cancer occurred at the rate of approximately 118 per 100,000 women.

* Incidence rates increased by 0.5 percent per year between 1987 and 1998.

* Much of the increase in incidence is attributed to reproductive factors, including

-- early menarche (at less than 12 years of age),

-- late menopause (55 years or more),

-- delayed childbearing or no full-term pregnancy,

-- lack of breastfeeding,

-- oral contraceptive use, and

-- postmenopausal obesity.

* Approximately 5 to 10 percent of breast cancer cases result from inherited mutation in breast cancer-susceptible genes.

* Environmental factors also may play an important role in the etiology of female breast cancer.

* Current use of oral contraceptives and prolonged use of hormone replacement therapy moderately increase risk.

* Evidence regarding organochlorine exposure and breast cancer risk is mixed.

* Atrazine is not associated with breast cancer risk, but dieldrin and lindane are.

* The effects of polychlorinated biphenyls (PCBs) vary according to the specific congeners involved.

* An observational study has linked benzene to breast cancer, but another case control study has refuted the association.

* The association of breast cancer risk with smoking is strong in families with a history of breast cancer, ovarian cancer, or both.

* Studies have shown a positive association of breast cancer with heterocyclic amines in women who eat well-done meat.

* Differing distribution of socio-demographic factors, including race/ethnicity, parity, and, possibly, nutritional status, may explain some of the inconsistencies across studies.

This department, "Practical Stuff!" originated from you, our readers. Many of you have expressed to us that one of the main reasons you read the Journal of Environmental Health is to glean practical and useful information for your everyday work-related activities. In response to your feedback, we dedicate this section to you with salient points to remember about two to three articles in each issue.