This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Rosenberg, L. Articles by Adams-Campbell, L. L. Search for Related Content PubMed PubMed Citation Articles by Rosenberg, L. Articles by Adams-Campbell, L. L.

A Follow-up Study of Physical Activity and Incidence of Colorectal Polyps in African-American Women

¹ Slone Epidemiology Center, Boston University, Boston, Massachusetts; ² National Heart, Lung, and Blood Institute, Bethesda, Maryland; and ³ Howard University Cancer Center, Washington, District of Columbia

Requests for reprints: Lynn Rosenberg, Slone Epidemiology Center, Boston University, 1010 Commonwealth Avenue, Boston, MA 02215. Phone: 617-734-6006; Fax: 617-738-5119. E-mail: lrosenberg{at}slone.bu.edu

Background: Physical activity is associated with a reduced risk of colon cancer, but the effect of activity on colorectal adenomas, which are precursors to colon cancer, is uncertain. The influence of physical activity on colorectal adenomas among African-American women is of particular interest because African-American women have an increased risk of colon cancer relative to other U.S. women.

Methods: We prospectively assessed the relation of physical activity to the incidence of colorectal polyps among African-American women. We followed 45,400 women in the Black Women's Health Study from 1997 to 2003. Data were obtained by biennial mailed questionnaires. During 287,029 person-years of follow-up, 1,390 women reported having been diagnosed with colorectal polyps. A review of medical records of 58 women who reported colorectal polyps indicated that 59% had adenomas and 41% had hyperplastic polyps. We converted hours per week of vigorous exercise and hours per week of walking to metabolic equivalent (MET)-hours. We estimated incidence rate ratios with Cox proportional hazard models, controlling for age, body mass index, smoking, family history of colorectal cancer, and education.

Results: For total MET-hours/wk spent in walking and vigorous exercise, the incidence rate ratio decreased from 0.94 for <5 MET-hours/wk to 0.72 for 40 MET-hours/wk (P_trend = 0.01). The inverse association was apparent among most subgroups examined, including women who may be at higher risk of colorectal adenomas because of being obese.

Conclusions: Increased physical activity is associated with a reduced incidence of colorectal polyps among African-American womend. (Cancer Epidemiol Biomarkers Prev 2006;15(8):1438–42)