Results from a recent multi-institutional study involving nearly 150,000 women indicate that long-term exposure to passive smoking is not associated with the development of breast cancer. Breast cancer is a common malignancy occurring in women in the United States with almost 200,000 new cases diagnosed each year and is the second leading cancer causing death in women in the U.S.
The probability of a person getting cancer depends on both genetic and non-genetic factors. A genetic factor is an inherited, unchangeable trait while a non-genetic factor is a changeable variable in a person’s environment. Some non-genetic factors play a role in facilitating the process of healthy cells turning cancerous while some cancers have no known environmental correlation but are known to have a genetic predisposition. This means a person may be at higher risk for a certain cancer if a family member has that type of cancer.
Recently, attention has been focused on defining associations between exposure to environmental factors, such as diet, stress, exercise, pollution and the development of certain cancers. Researchers continue to work toward determining what factors may contribute to the development of different types of cancer so that better strategies for prevention and/or screening can be produced and implemented.
Passive exposure to tobacco smoke has been implicated as a risk factor for adult lung cancer, acute respiratory disorders in children, reduced pulmonary (lung) function, respiratory infections and possibly heart disease. Some previous studies have claimed to have found associations between passive exposure to tobacco smoke (second-hand smoke) and the development of breast cancer. Due to the controversial implementation and interpretation of these studies, researchers from the University of Medicine and Dentistry of New Jersey, the American Cancer Society, the Robert Wood Johnson Medical School and the Environmental Protection Agency conducted a large, controlled study in an attempt to determine effects of long-term passive exposure to tobacco smoke on the development of breast cancer.
The clinical study began in 1982 and involved nearly 150,000 women who were non-smokers. These women were divided into two groups – those who were married to a smoker, or those who were married to a non-smoker. All of the women evaluated were married to the same spouse for the duration of the study. Twelve years after the initiation of the study, 669 women had died of breast cancer. Overall, there was no association found between passive exposure to tobacco smoke and breast cancer death in these women. While this study suggests there is not a relationship between passive smoking and breast cancer, longer follow-up is necessary. Researchers will continue to evaluate other possible associations between passive smoking and other environmental factors and the development of cancers.
(Journal of the National Cancer Institute, Vol 92, No 20, pp 1666-1673, 2000)