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Physical activity and postmenopausal breast cancer: proposed biologic mechanisms and areas for future research.

Abstract

Convincing evidence now supports a probable preventive role for physical activity in postmenopausal breast cancer. The mechanisms by which long-term physical activity affect risk, however, remain unclear. The aims of this review were to propose a biological model whereby long-term physical activity lowers postmenopausal breast cancer risk and to highlight gaps in the epidemiologic literature. To address the second aim, we summarized epidemiologic literature on 10 proposed biomarkers, namely, body mass index (BMI), estrogens, androgens, sex hormone binding globulin, leptin, adiponectin, markers of insulin resistance, tumor necrosis factor-alpha, interleukin-6, and C-reactive protein, in relation to postmenopausal breast cancer risk and physical activity, respectively. Associations were deemed "convincing," "probable," "possible," or "hypothesized" using set criteria. Our proposed biological model illustrated the co-occurrence of overweight/obesity, insulin resistance, and chronic inflammation influencing cancer risk through interrelated mechanisms. The most convincing epidemiologic evidence supported associations between postmenopausal breast cancer risk and BMI, estrogens, and androgens, respectively. In relation to physical activity, associations were most convincing for BMI, estrone, insulin resistance, and C-reactive protein. Only BMI and estrone were convincingly (or probably) associated with both postmenopausal breast cancer risk and physical activity. There is a need for prospective cohort studies relating the proposed biomarkers to cancer risk and for long-term exercise randomized controlled trials comparing biomarker changes over time, specifically in postmenopausal women. Future etiologic studies should consider interactions among biomarkers, whereas exercise trials should explore exercise effects independently of weight loss, different exercise prescriptions, and effects on central adiposity.

Authors+Show Affiliations

Division of Population Health, Alberta Cancer Board, 1331-29 Street NW, Calgary, Alberta, Canada T2N 4N2.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

19124476

Citation

Neilson, Heather K., et al. "Physical Activity and Postmenopausal Breast Cancer: Proposed Biologic Mechanisms and Areas for Future Research." Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored By the American Society of Preventive Oncology, vol. 18, no. 1, 2009, pp. 11-27.
Neilson HK, Friedenreich CM, Brockton NT, et al. Physical activity and postmenopausal breast cancer: proposed biologic mechanisms and areas for future research. Cancer Epidemiol Biomarkers Prev. 2009;18(1):11-27.
Neilson, H. K., Friedenreich, C. M., Brockton, N. T., & Millikan, R. C. (2009). Physical activity and postmenopausal breast cancer: proposed biologic mechanisms and areas for future research. Cancer Epidemiology, Biomarkers & Prevention : a Publication of the American Association for Cancer Research, Cosponsored By the American Society of Preventive Oncology, 18(1), pp. 11-27. doi:10.1158/1055-9965.EPI-08-0756.
Neilson HK, et al. Physical Activity and Postmenopausal Breast Cancer: Proposed Biologic Mechanisms and Areas for Future Research. Cancer Epidemiol Biomarkers Prev. 2009;18(1):11-27. PubMed PMID: 19124476.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Physical activity and postmenopausal breast cancer: proposed biologic mechanisms and areas for future research. AU - Neilson,Heather K, AU - Friedenreich,Christine M, AU - Brockton,Nigel T, AU - Millikan,Robert C, PY - 2009/1/7/entrez PY - 2009/1/7/pubmed PY - 2009/3/4/medline SP - 11 EP - 27 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 - 18 IS - 1 N2 - Convincing evidence now supports a probable preventive role for physical activity in postmenopausal breast cancer. The mechanisms by which long-term physical activity affect risk, however, remain unclear. The aims of this review were to propose a biological model whereby long-term physical activity lowers postmenopausal breast cancer risk and to highlight gaps in the epidemiologic literature. To address the second aim, we summarized epidemiologic literature on 10 proposed biomarkers, namely, body mass index (BMI), estrogens, androgens, sex hormone binding globulin, leptin, adiponectin, markers of insulin resistance, tumor necrosis factor-alpha, interleukin-6, and C-reactive protein, in relation to postmenopausal breast cancer risk and physical activity, respectively. Associations were deemed "convincing," "probable," "possible," or "hypothesized" using set criteria. Our proposed biological model illustrated the co-occurrence of overweight/obesity, insulin resistance, and chronic inflammation influencing cancer risk through interrelated mechanisms. The most convincing epidemiologic evidence supported associations between postmenopausal breast cancer risk and BMI, estrogens, and androgens, respectively. In relation to physical activity, associations were most convincing for BMI, estrone, insulin resistance, and C-reactive protein. Only BMI and estrone were convincingly (or probably) associated with both postmenopausal breast cancer risk and physical activity. There is a need for prospective cohort studies relating the proposed biomarkers to cancer risk and for long-term exercise randomized controlled trials comparing biomarker changes over time, specifically in postmenopausal women. Future etiologic studies should consider interactions among biomarkers, whereas exercise trials should explore exercise effects independently of weight loss, different exercise prescriptions, and effects on central adiposity. SN - 1055-9965 UR - https://www.unboundmedicine.com/medline/citation/19124476/Physical_activity_and_postmenopausal_breast_cancer:_proposed_biologic_mechanisms_and_areas_for_future_research_ L2 - http://cebp.aacrjournals.org/cgi/pmidlookup?view=long&pmid=19124476 DB - PRIME DP - Unbound Medicine ER -