Summary/Abstract This is a competing renewal application that requests continued support for providing pre- and post-doctoral trainees with strong methodological and practical training in quantitative cancer research. The application leverages a unique combination of strengths from the Harvard T.H. Chan School of Public Health (HCSPH), Dana-Farber Cancer Institute (DFCI) and Dana-Farber / Harvard Cancer Center. This training program, now in its 39th year, draws upon a distinguished faculty, consisting of biostatisticians, computational biologists, and other data scientists, as well as world renowned experts in cancer treatment and research. Its overarching goal is to provide the trainees with all essential elements of training needed to successfully undertake current cancer research. The specific goals of this training program are to train students and postdoctoral fellows to be(1)quantitative scientists in cancer research, who are capable of using probability, statistics, computer science and mathematics to increase our knowledge and understanding of cancer; (2) strong team leaders/players as well as excellent communicators in a cancer research environment, who can effectively disseminate their research results and assume active roles in the design, analysis and interpretation of cancer clinical trials, cancer population studies and cancer genomic studies. All predoctoral students supported by this training grant are required to take a cognate concentration in cancer-related courses. During their first and second summer periods in the program, students are required to participate in research activities, typically performed under the supervision of faculty mentors affiliated with the program. Afterwards, many of these students will take up residence at the DFCI or elsewhere at DFHCC and continue their research in cancer, which eventually evolves into their dissertation projects. All the postdoctoral fellows are closely involved with the practice of quantitative sciences in cancer and are typically in residence at the DFCI. All trainees are required to actively participate in the a working group seminar series on quantitative issues in cancer research, which serves as a primary forum at Harvard to discuss current issues and challenges on this topic, as well as in several of the DFHCC sponsored symposia and event. This proposal requests 5 years of funding to support 10 pre-doctoral students and 1 post-doctoral fellow annually.