Tricia M. Peters
B.A. Colgate University, 2003
M.Phil. University of Cambridge (Darwin College), 2006
Ph.D. University of Cambridge (Darwin College), 2009

4th Year Medical Student

Advisors: Michael Leitzmann, M.D., Dr. PH; Nick Wareham, MBBS, Ph.D.;
Ulf Ekelund, Ph.D.

Department: National Cancer Institute; MRC Epidemiology Unit

Graduate Program: Epidemiology

Title:  Physical activity and postmenopausal breast cancer risk in the NIH-AARP Diet and Health study

Preceptor: Dr. Michael Leitzmann, Division of Cancer Epidemiology & Genetics, NIH

Abstract (Ph.D.):

Tricia M. Peters,¹,³ Arthur Schatzkin,¹ Gretchen L. Gierach,²,⁵ Steven C. Moore,¹ James V. Lacey, Jr.,² Nicholas J. Wareham,³ Ulf Ekelund,³ Albert R. Hollenbeck,⁴ and Michael F. Leitzmann⁶

¹Nutritional Epidemiology Branch, Division of Cancer Epidemiology and Genetics,   National Cancer Institute, NIH, Bethesda, MD
²Hormonal and Reproductive Epidemiology Branch, Division of Cancer Epidemiology
  and Genetics, National Cancer Institute, NIH, Bethesda, MD.
³MRC Epidemiology Unit, Institute of Metabolic Science, Cambridge, UK.
⁴AARP, Washington, DC.
⁵Cancer Prevention Fellowship Program, Office of Preventive Oncology, National
  Cancer Institute, NIH, DHHS, Bethesda, MD.
⁶Regensburg University Medical Center, Regensburg, Germany

BACKGROUND: Breast cancer is recognized as the most common cancer affecting U.S. women. Among the few modifiable risk factors for breast cancer, a high versus low level of physical activity has been consistently associated with 20-40% reduced risk of postmenopausal breast cancer. However, it is unclear whether this association varies across breast cancer tumor subtypes or is modified by reproductive and lifestyle factors.

METHODS: We examined the association of physical activity with postmenopausal breast cancer risk in 182,862 U.S. women in the NIH-AARP Diet and Health Study cohort. Physical activity was assessed by self-report at baseline (1995-1996), and 6,609 incident breast cancers were identified through December 31, 2003. Cox regression was used to estimate the relative risk (RR) and 95% confidence intervals (95%CI) of postmenopausal breast cancer overall and by tumor characteristics. Effect modification by select reproductive and lifestyle factors was also explored.

RESULTS: In multivariate models, physical activity was associated with reduced breast cancer risk, and the most active women experienced a 13% lower risk than inactive women (RR=0.87; 95%CI:0.81,0.95). This inverse relationship was not modified by tumor stage or histology, but was suggestively stronger for estrogen receptor (ER)-negative than for ER-positive breast tumors. The relationship was more pronounced among women who had never used menopausal hormone therapy and women with a family history of breast cancer, and also appeared stronger for overweight/obese women.

CONCLUSIONS: A high level of physical activity was associated with reduced postmenopausal breast cancer risk, particular to ER-negative tumors. These results, along with heterogeneity in the physical activity-breast cancer relationship for subgroups of menopausal hormone therapy use, indicate that physical activity likely operates via estrogen-independent and estrogenic mechanisms to influence breast cancer risk.

Publications:
(pre-MSTP publications indicated with an *)

*Peters TM, et al. (on behalf of the InterAct Consortium). Validity of a short questionnaire to assess physical activity in 10 European countries. European Journal of Epidemiology. 2012 Jan; 27(1): 15-25.

*Peters TM, S Brage, K Westgate, et al. The InterAct Consortium: Validity of the short European Prospective Investigation into Cancer and Nutrition (EPIC) Questionnaire to assess physical activity in 10 European countries. In submission.

*Peters TM, XO Shu, SC Moore, et al. (2010). Validity of a physical activity questionnaire in Shanghai. Medicine and Science in Sports and Exercise. 42(12):2222-30.

*Peters TM, SC Moore, YB Xiang, et al. (2010). Accelerometer-measured physical activity in Chinese adults. American Journal of Preventive Medicine, 38(6):583-91.

*Peters TM, A Schatzkin, GL Gierach, SC Moore, JV Lacey Jr, NJ Wareham, U Ekelund, AR Hollenbeck, MF Leitzmann. (2009). Physical activity and postmenopausal breast cancer risk in the NIH-AARP Diet and Health study. CEBP 18(1):289-96.

*Moore SC, TM Peters, J Ahn, et al. (2009). Age-specific physical activity and prostate cancer risk among white men and black men. Cancer. 115(21):5060-70.

*Peters TM, SC Moore, GL Gierach, et al. (2009). Intensity and timing of physical activity in relation to postmenopausal breast cancer risk: the prospective NIH-AARP Diet and Health Study. BMC Cancer, 9:349.

*Moore SC, TM Peters, J Ahn, Y Park, A Schatzkin, D Albanes, R Ballard-Barbash, A Hollenbeck, MF Leitzmann. (2008). Physical activity in relation to total, advanced, and fatal prostate cancer. CEBP. 17(9):2458-66.

*Leitzmann MF, SC Moore, TM Peters, JV Lacey Jr, A Schatzkin, C Schairer, LA Brinton, D Albanes. (2008). Prospective study of physical activity and risk of postmenopausal breast cancer. Cancer Res. 10(5):R92.

*Lipska B, T Peters, TM Hyde, N Halim, C Horowitz, S Mitkus, C Shannon-Weickert, M Matsumoto, A Sawa, R Straub, R Vakkalanka, MM Herman, DR Weinberger, JE Kleinman. (2006). Expression of DISC1 binding partners is reduced in schizophrenia and associated with DISC1 SNPs. Human Molecular Genetics. 15(8):1245-1258.

*Peters TM, U Ekelund, MF Leitzmann, D Easton, R Warren, R Luben, S Bingham, KT Khaw, NJ Wareham. (2007). Physical Activity and Mammographic Breast Density in the EPIC-Norfolk Cohort Study. American Journal of Epidemiology. 167(5):579-585.