With a long background as a practicing surgeon with a focus on oncology, I have always conducted clinical and epidemiologic research in parallel. My clinical research includes randomized trials, prognostic studies, and studies of clinical issues using an observational study design. Over the years, however, my focus has been on cancer epidemiology, and I have worked on a large number of cancer sites and types. Currently, I am working predominantly on prostate cancer, (with research ranging from genetic association studies to randomized trials of radical surgical treatment, and prediction of outcome using molecular and genetic markers), malignant lymphomas, cervical cancer (with a focus on viral load as a possible determinant of progression from precursors to invasive cancer), and breast cancer. I am also the PI of an NIH funded large molecular epidemiologic case-control study of nasopharyngeal carcinoma in China with enrollment of participants ending during the fall of 2014. Finally, through an affiliation with Oslo University, I am involved in a randomized screening trial of colonoscopy as well as studies of cancer risk among patients with large bowel adenomas and planned randomized trials of surveillance strategies following adenoma removal. Lastly, I am involved in planning a large-scale prospective study focusing on non-communicable diseases in sub-Saharan Africa.