He is especially interested in the effects of reproductive factors, diet, genetic predisposition, histopathologic factors, occupational/environmental/medication exposures, infection and immune functioning in cancer etiology. His major research projects have included studies of ovarian cancer, pancreas cancer, lung cancer, bladder cancer, esophageal and stomach cancer, and of cancers related to usage of oral contraceptives and noncontraceptive estrogens. Dr. Risch is Associate Editor of the Journal of the National Cancer Institute, Editor of the International Journal of Cancer, and for six years was a Member of the Board of Editors, the American Journal of Epidemiology. Dr. Risch is an author of more than 400 original peer-reviewed research publications in the medical literature and those research papers have been cited by other scientific publications more than 53,750 times.