7. Project Summary We propose to renew the NCI Cancer Epidemiology Training Program. We propose to continue to support 12 trainees per year, but have adjusted the proportions to meet NCI recommendations, and propose three pre-doctoral students and nine postdoctoral fellows. We leverage the enormously rich academic environment of the Harvard T.H. Chan School of Public Health, together with the Dana- Farber/Harvard Cancer Center, Channing Division of Network Medicine and a multitude of affiliated institutions. These resources include the Harvard cohorts (Nurses’ Health Studies I,II, and III, Health Professionals Follow-up Study, Physicians’ Health Study, Women’s Health Study, the VITAL trial,and others). These cohorts have millions of person-years of repeated follow-up for all cancer sites, as well as blood and tissue samples from over 100,000 individuals. The opportunities for cancer research within this environment are virtually limitless. We have brought together outstanding faculty mentors to provide integrated interdisciplinary experiences and collaborative interactions, a specialized curriculum with core and elective coursework, nondidactic practical career training, individual candidate training plans, and ongoing Program evaluation. Cutting-edge didactic training and mentoring will create a new generation of highly skilled and enthusiastic investigators to study factors that influence cancer incidence and survival. A major focus is to take advantage of the multitude of modern ‘omics methods, such as genomics, metabolomics, together with the array of biologic samples, including blood, oral swabs and stool for microbiome, and tumor tissue. The multidisciplinary training will include applying modern epidemiologic and biostatistical methods to analyze such data, and develop novel approaches for cancer research. This training program is currently in year 42; we have constantly updated the program, taking advantage of approaches that work well, initiating new aspects, and taking advantage of new opportunities, and revise our mentor group accordingly. One constant feature is that we have never had a shortage of outstanding candidates for the program. With continued support, we believe this training program will continue to have a major impact to further the mission of NCI to reduce the burden of cancer through prevention and improved survival.