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A prospective study of recreational physical activity and breast cancer risk.
Arch Intern Med 1999; 159(19):2290-6AI

Abstract

BACKGROUND

Increased physical activity has been hypothesized to prevent breast cancer, largely by reducing cumulative lifetime exposure to circulating ovarian hormones. However, epidemiologic findings are inconsistent, and there is no consensus on the best way to quantify physical activity. We thus examined this issue in a large cohort of women, using several different measures of adult physical activity.

METHODS

We analyzed data from the Nurses' Health Study, a prospective study of women aged 30 to 55 years in 1976. In 1980 and on subsequent surveys, women were asked about the average number of hours per week spent in various moderate and vigorous recreational physical activity during the past year. We computed a "baseline-only" (1980) measure of hours per week of physical activity, as well as a cumulative average measure that used updated reports on physical activity. During 16 years of follow-up, we identified 3137 cases of invasive breast cancer (1036 premenopausal and 2101 postmenopausal women). Data were analyzed by use of multivariate pooled logistic regression to produce relative risks of breast cancer, and the associated confidence intervals.

RESULTS

Women who were more physically active in adulthood had a lower risk of breast cancer than those who were less physically active. Comparing those who reported engaging in moderate or vigorous physical activity for 7 or more hours per week with those who engaged in such physical activity for less than 1 hour per week, the relative risk was 0.82 (95% confidence interval, 0.70-0.97), using the cumulative average updating. The dose-response trend was statistically significant (P = .004). Using the baseline-only measure of physical activity produced slightly weaker relative risks.

CONCLUSION

These results contribute to the body of evidence suggesting that higher levels of adult physical activity afford modest protection against breast cancer.

Authors+Show Affiliations

Channing Laboratory, Boston, MA 02115, USA. beverly.rockhill@channing.harvard.edu

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

10547168

Citation

Rockhill, B, et al. "A Prospective Study of Recreational Physical Activity and Breast Cancer Risk." Archives of Internal Medicine, vol. 159, no. 19, 1999, pp. 2290-6.
Rockhill B, Willett WC, Hunter DJ, et al. A prospective study of recreational physical activity and breast cancer risk. Arch Intern Med. 1999;159(19):2290-6.
Rockhill, B., Willett, W. C., Hunter, D. J., Manson, J. E., Hankinson, S. E., & Colditz, G. A. (1999). A prospective study of recreational physical activity and breast cancer risk. Archives of Internal Medicine, 159(19), pp. 2290-6.
Rockhill B, et al. A Prospective Study of Recreational Physical Activity and Breast Cancer Risk. Arch Intern Med. 1999 Oct 25;159(19):2290-6. PubMed PMID: 10547168.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - A prospective study of recreational physical activity and breast cancer risk. AU - Rockhill,B, AU - Willett,W C, AU - Hunter,D J, AU - Manson,J E, AU - Hankinson,S E, AU - Colditz,G A, PY - 1999/11/5/pubmed PY - 1999/11/5/medline PY - 1999/11/5/entrez SP - 2290 EP - 6 JF - Archives of internal medicine JO - Arch. Intern. Med. VL - 159 IS - 19 N2 - BACKGROUND: Increased physical activity has been hypothesized to prevent breast cancer, largely by reducing cumulative lifetime exposure to circulating ovarian hormones. However, epidemiologic findings are inconsistent, and there is no consensus on the best way to quantify physical activity. We thus examined this issue in a large cohort of women, using several different measures of adult physical activity. METHODS: We analyzed data from the Nurses' Health Study, a prospective study of women aged 30 to 55 years in 1976. In 1980 and on subsequent surveys, women were asked about the average number of hours per week spent in various moderate and vigorous recreational physical activity during the past year. We computed a "baseline-only" (1980) measure of hours per week of physical activity, as well as a cumulative average measure that used updated reports on physical activity. During 16 years of follow-up, we identified 3137 cases of invasive breast cancer (1036 premenopausal and 2101 postmenopausal women). Data were analyzed by use of multivariate pooled logistic regression to produce relative risks of breast cancer, and the associated confidence intervals. RESULTS: Women who were more physically active in adulthood had a lower risk of breast cancer than those who were less physically active. Comparing those who reported engaging in moderate or vigorous physical activity for 7 or more hours per week with those who engaged in such physical activity for less than 1 hour per week, the relative risk was 0.82 (95% confidence interval, 0.70-0.97), using the cumulative average updating. The dose-response trend was statistically significant (P = .004). Using the baseline-only measure of physical activity produced slightly weaker relative risks. CONCLUSION: These results contribute to the body of evidence suggesting that higher levels of adult physical activity afford modest protection against breast cancer. SN - 0003-9926 UR - https://www.unboundmedicine.com/medline/citation/10547168/A_prospective_study_of_recreational_physical_activity_and_breast_cancer_risk_ L2 - https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/vol/159/pg/2290 DB - PRIME DP - Unbound Medicine ER -