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Physical activity and colon cancer risk among women in the California Teachers Study.

Abstract

BACKGROUND

Existing data suggest that physical activity reduces colon cancer risk, but the association is not consistently observed in women. One potential explanation for this inconsistency is that hormone therapy, which is associated with lower colon cancer risk, acts as a modifier of the physical activity/colon cancer relationship.

METHODS

Participants in the California Teachers Study (N = 120,147), a prospective cohort of female teachers and administrators residing in California, ages 22 to 84 years at baseline and with no prior history of colon cancer were eligible for study. Between 1996 and 2002, 395 patients were diagnosed with invasive colon cancer. The relative risks (RR) associated with lifetime (high school through age 54 years or current age) and recent (past 3 years) strenuous and moderate recreational physical activity were estimated using Cox proportional hazards regression models.

RESULTS

Combined lifetime moderate and strenuous recreational physical activity was only modestly associated with colon cancer risk in the cohort [>or=4 versus <or=0.5 h/wk/y: RR, 0.75; 95% confidence interval, 0.57-1.00; P(trend) = 0.23]. Lifetime physical activity reduced colon cancer risk among postmenopausal women who had never taken hormone therapy (>or=4 versus <or=0.5 h/wk/y: RR, 0.51; 95% confidence interval, 0.31-0.85; P(trend) = 0.02). Postmenopausal women with histories of hormone therapy use had lower colon cancer risk, but their risk was not associated with physical activity. The likelihood ratio test for interaction between hormone use and lifetime moderate plus strenuous physical activity was of borderline statistical significance (P = 0.05). We observed no effect modification by age, body mass index, smoking status, menopausal status, or folate intake.

CONCLUSIONS

Lifetime recreational physical activity may protect against colon cancer among postmenopausal women who have never used hormone therapy. Among hormone therapy users, who have lower risk of colon cancer, recreational physical activity does not seem to provide any additional benefit. With declining rates of hormone therapy use, physical activity offers one possible means for reducing women's colon cancer risk.

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  • Authors+Show Affiliations

    ,

    Clinical Cancer Genetics Department, City of Hope National Medical Center, Duarte, CA, USA.

    , , , , , , , , , , , ,

    Source

    MeSH

    Adult
    Aged
    Aged, 80 and over
    California
    Chi-Square Distribution
    Colonic Neoplasms
    Faculty
    Female
    Hormone Replacement Therapy
    Humans
    Middle Aged
    Motor Activity
    Postmenopause
    Proportional Hazards Models
    Prospective Studies
    Risk Factors

    Pub Type(s)

    Journal Article
    Research Support, N.I.H., Extramural
    Research Support, Non-U.S. Gov't
    Research Support, U.S. Gov't, P.H.S.

    Language

    eng

    PubMed ID

    17372247

    Citation

    Mai, Phuong L., et al. "Physical Activity and Colon Cancer Risk Among Women in the California Teachers Study." Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored By the American Society of Preventive Oncology, vol. 16, no. 3, 2007, pp. 517-25.
    Mai PL, Sullivan-Halley J, Ursin G, et al. Physical activity and colon cancer risk among women in the California Teachers Study. Cancer Epidemiol Biomarkers Prev. 2007;16(3):517-25.
    Mai, P. L., Sullivan-Halley, J., Ursin, G., Stram, D. O., Deapen, D., Villaluna, D., ... Bernstein, L. (2007). Physical activity and colon cancer risk among women in the California Teachers Study. Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored By the American Society of Preventive Oncology, 16(3), pp. 517-25.
    Mai PL, et al. Physical Activity and Colon Cancer Risk Among Women in the California Teachers Study. Cancer Epidemiol Biomarkers Prev. 2007;16(3):517-25. PubMed PMID: 17372247.
    * Article titles in AMA citation format should be in sentence-case
    TY - JOUR T1 - Physical activity and colon cancer risk among women in the California Teachers Study. AU - Mai,Phuong L, AU - Sullivan-Halley,Jane, AU - Ursin,Giske, AU - Stram,Daniel O, AU - Deapen,Dennis, AU - Villaluna,Doojduen, AU - Horn-Ross,Pamela L, AU - Clarke,Christina A, AU - Reynolds,Peggy, AU - Ross,Ronald K, AU - West,Dee W, AU - Anton-Culver,Hoda, AU - Ziogas,Argyrios, AU - Bernstein,Leslie, PY - 2007/3/21/pubmed PY - 2007/5/4/medline PY - 2007/3/21/entrez SP - 517 EP - 25 JF - Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology JO - Cancer Epidemiol. Biomarkers Prev. VL - 16 IS - 3 N2 - BACKGROUND: Existing data suggest that physical activity reduces colon cancer risk, but the association is not consistently observed in women. One potential explanation for this inconsistency is that hormone therapy, which is associated with lower colon cancer risk, acts as a modifier of the physical activity/colon cancer relationship. METHODS: Participants in the California Teachers Study (N = 120,147), a prospective cohort of female teachers and administrators residing in California, ages 22 to 84 years at baseline and with no prior history of colon cancer were eligible for study. Between 1996 and 2002, 395 patients were diagnosed with invasive colon cancer. The relative risks (RR) associated with lifetime (high school through age 54 years or current age) and recent (past 3 years) strenuous and moderate recreational physical activity were estimated using Cox proportional hazards regression models. RESULTS: Combined lifetime moderate and strenuous recreational physical activity was only modestly associated with colon cancer risk in the cohort [>or=4 versus <or=0.5 h/wk/y: RR, 0.75; 95% confidence interval, 0.57-1.00; P(trend) = 0.23]. Lifetime physical activity reduced colon cancer risk among postmenopausal women who had never taken hormone therapy (>or=4 versus <or=0.5 h/wk/y: RR, 0.51; 95% confidence interval, 0.31-0.85; P(trend) = 0.02). Postmenopausal women with histories of hormone therapy use had lower colon cancer risk, but their risk was not associated with physical activity. The likelihood ratio test for interaction between hormone use and lifetime moderate plus strenuous physical activity was of borderline statistical significance (P = 0.05). We observed no effect modification by age, body mass index, smoking status, menopausal status, or folate intake. CONCLUSIONS: Lifetime recreational physical activity may protect against colon cancer among postmenopausal women who have never used hormone therapy. Among hormone therapy users, who have lower risk of colon cancer, recreational physical activity does not seem to provide any additional benefit. With declining rates of hormone therapy use, physical activity offers one possible means for reducing women's colon cancer risk. SN - 1055-9965 UR - https://www.unboundmedicine.com/medline/citation/17372247/full_citation L2 - http://cebp.aacrjournals.org/cgi/pmidlookup?view=long&amp;pmid=17372247 DB - PRIME DP - Unbound Medicine ER -