Biography

Dr. Leitzmann received an M.D. from the University of Berlin, Germany in 1986, followed by a fellowship in sports physiology and a medical residency in Internal Medicine. In 1995, Dr. Leitzmann joined the Harvard School of Public Health, where he received an M.P.H. with a concentration in Quantitative Methods in 1996 and a doctorate in Epidemiology and Nutritional Epidemiology in 2000. He completed two years of postdoctoral research in the Epidemiology Department at Harvard, and joined the NCI as an Investigator in the Nutritional Epidemiology Branch in 2002.

Research Interests

• Physical activity, diet, body size, and cancer
• Dietary and lifestyle risk factors for prostate cancer

Research

I am focusing on three areas of research to elucidate the interrelationship between physical activity, diet, body size, and cancer risk: (1) methodological research on the assessment of physical activity and its individual components; (2) clarification of biologic mechanisms linking the adverse effects of physical inactivity, energy oversupply, and obesity to cancer risk; and (3) investigation of the independent and joint relations of physical activity, diet, and body size to cancers of various sites, notably cancers of the colon, breast, and prostate.

Methodological research on the assessment of physical activity

The ability to precisely assess physical activity in population studies of disease etiology has significant public health relevance. One of my goals is to develop methods to improve the measurement of physical activity and inactivity in free-living individuals. Activity monitors provide an objective assessment of physical activity in population studies. I am currently conducting a study in collaboration with Vanderbilt University and the Shanghai Cancer Institute to develop a comprehensive physical activity questionnaire and to assess the validity and reliability of this instrument using activity monitors and a fitness test. This study is being conducted among women and men enrolled in the Shanghai Women's Cohort Study and the Shanghai Men's Cohort Study.

Clarification of biologic mechanisms linking the adverse effects of physical inactivity, energy oversupply, and obesity to cancer risk

The mechanisms by which energy imbalance may modulate cancer risk are heterogeneous. I intend to examine specific etiologic pathways that might underlie the interrelationship between physical activity, energy intake, body size, and cancer risk, including insulin resistance and lipid metabolism, insulin-like growth factors, steroid hormones, immune function, and inflammatory factors. The primary resources for this aspect of my research are the ATBC (Alpha-Tocopherol Beta-Carotene) Cancer Prevention Study, the PPT (Polyp Prevention Trial), the PLCO (Prostate, Lung, Colorectal, and Ovarian) Cancer Screening Trial, and the CONCeRN (Colorectal Neoplasia screening with Colonoscopy in asymptomatic, average-risk women at Regional Navy/army centers).

Investigation of the independent and joint relations of physical activity, diet, and body size to cancers of various sites

Epidemiologic studies show inverse associations between physical activity and several cancers. In contrast, overweight and obese individuals are at increased risk for cancer. Energy balance is determined both by energy expenditure (physical activity) and energy intake, and obesity is usually the consequence of a positive energy imbalance. However, the relation of energy balance to cancer risk has not been well studied in humans. I am currently conducting a simultaneous exploration of physical activity, energy intake, and body size and their impact on risk of cancer of various sites in the NCI-AARP Diet and Health Study, a prospective cohort study of 567,000 U.S. men and women with detailed data on physical activity, diet, and anthropometric variables. Specifically, I will address whether a sedentary lifestyle and an energy-rich diet individually or in combination influence cancer development or whether the mechanism is through obesity.

Prostate Cancer

There are currently only three established risk factors for prostate cancer: older age, a positive family history of prostate cancer, and race. In addition to these non-modifiable risk factors for prostate cancer, a number of dietary and lifestyle factors have been proposed as contributing factors to prostate cancer. These factors may provide important opportunities for prevention of this malignancy. In the Health Professionals Follow-up Study (HPFS) cohort at Harvard, for example, we reported a suggestive decreased risk of advanced prostate cancer among men with regular aspirin use. In contrast, we observed an increased risk of advanced prostate cancer among men with high intake of zinc supplements. We also noted that high energy intake was associated with an increased risk of advanced prostate cancer especially for cases with a young age at diagnosis or a positive family history of prostate cancer. Further research in this area will enhance our understanding of the pathogenesis of prostate cancer and facilitate efforts to prevent this malignancy.

Keywords

Physical activity, physical fitness, energy balance, dietary factors, lifestyle factors, nutritional epidemiology, prostate cancer

Selected Publications

• Leitzmann MF, et al. "Zinc supplement use and risk of prostate cancer." J Natl Cancer Inst 2003;95:1004-7.
• Platz EA, et al. "Interrelation of energy intake, body size, and physical activity with prostate cancer in a large prospective cohort study." Cancer Res 2003;63:8542-8.
• Leitzmann MF, et al. "Aspirin use in relation to risk of prostate cancer." Cancer Epidemiol Biomarkers Prev 2002;11:1108-1.
• Leitzmann MF, et al "Recreational physical activity and the risk of cholecystectomy in women." N Engl J Med 1999;341:777-84.

Collaborators

DCEG Collaborators

• Demetrius Albanes, M.D.; Aaron Blair, Ph.D.; Wong-Ho Chow, Ph.D.; Patricia Hartge, Sc.D.; Michael Hauptmann, Ph.D.; Richard Hayes, D.D.S., Ph.D., M.P.H.; Robert Hoover, M.D., Sc.D.; Ann Hsing, Ph.D.; Bu-Tian Ji, M.D., Ph.D.; James Lacey, Ph.D.; Ulrike Peters, Ph.D.; Ruth Pfeiffer, Ph.D.; Catherine Schairer, Ph.D.; Arthur Schatzkin, M.D. Dr.P.H.; Rachael Stolzenberg-Solomon, Ph.D., M.P.H.; Sholom Wacholder, Ph.D.; Regina Ziegler, Ph.D.

Other NCI Collaborators

• Rachel Ballard-Barbash, M.D., M.P.H.; Victor Kipnis, Ph.D.; Amy Subar, Ph.D.; Frances Thompson, Ph.D.; Richard Troiano, Ph.D.

Other Scientific Collaborators

• June Chan, Sc.D.; University of California San Francisco, CA
• Andrew Flood, Ph.D.; University of Minnesota, Minneapolis, MN
• Yu-Tang Gao, M.D.; Shanghai Cancer Institute, Shanghai, China
• Edward Giovannucci, M.D., Sc.D.; Harvard School of Public Health, Boston, MA
• Charles Mathews, Ph.D.; Vanderbilt University, Nashville, TN
• Elizabeth Platz, Sc.D., M.P.H.; Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
• Xiao Ou Shu, M.D., Ph.D.; Vanderbilt University, Nashville, TN
• Stephanie Smith-Warner, Ph.D.; Harvard School of Public Health, Boston, MA
• Chung-Jyi Tsai, M.D., Sc.D.; University of Iowa, Iowa City, IA