Exercise and physical health: Cancer and immune function

Journal/Book: Res Quart Exercise Sport. 1995; 66: 1900 Association Drive, Reston, VA 22091. Amer Alliance Health Phys Educ Rec & Dance. 286-291.

Abstract: Cancer is a leading cause of morbidity and mortality in developed countries. In the United States, with a population of about 250 million, the American Cancer Society estimated that 1.21 million new cases of cancer developed in 1994, while 0.54 million people died from this disease that same year (Boring, Squires, Tong, & Montgomery, 1994). In recent years, several epidemiological studies have suggested a link between physical inactivity and increased cancer risk (see Lee, 1994, for a review). Biologically, it appears plausible for higher levels of physical activity to decrease cancer risk, as various studies have shown that moderate exercise can enhance the human immune system. This will be discussed later in the paper. Additionally, for site-specific cancers, other mechanisms also may underlie the inverse association seen with physical activity. With colon cancer, exercise may decrease risk by shortening transit time within the intestine, thereby decreasing contact between potential carcinogens, cocarcinogens, or promoters in the fecal stream (Lee, 1994). For female and male reproductive cancers, reproductive hormones play an important role in their etiology and spread. Several studies have shown that exercise can alter the levels of these hormones, potentially decreasing risks of these reproductive cancers (Lee, 1994). This paper will first review the epidemiological literature on physical activity and the risk of developing various site-specific cancers. Then the effect of exercise on the human immune system will be discussed. Finally, because the immune system also regulates susceptibility to and recovery from infections, data on the relation between exercise and one kind of infection, upper respiratory tract infection, will be summarized.

Note: Article IM Lee, Harvard Univ, Brigham & Womens Hosp, Sch Med, Boston, MA 02115 USA

Keyword(s): exercise; cancer; immune system; NATURAL-KILLER-CELLS; COLON CANCER; COLORECTAL-CANCER; RISK; SHANGHAI; DISEASE; TURKEY; BREAST; MALES

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