Following his MD from Tulane Medical School, he completed a general surgery residency in San Francisco and this was followed by a two-year surgical oncology fellowship at the Roswell Park Cancer Institute in Buffalo, New York.

Dr. Petrelli is the Bank of America Medical Director of the Helen F. Graham Cancer Center at the Christiana Care Health Services and Professor of Surgery at Thomas Jefferson University. He came to CCHS from the Roswell Park Cancer Institute where he was Chief of Surgery and Director of the Surgical Oncology Fellowship Program. In his present position, Dr. Petrelli has responsibility for overseeing and developing the Cancer Clinical and Research Program at Christiana Care. He has established the Multi-Disciplinary Disease Site Centers at the Helen F. Graham Cancer Center for the diagnosis and treatment of cancer as a first in the State of Delaware.

Dr. Petrelli has over 200 publications in peer-reviewed journals and is the author of thirty-two book chapters in the field of colorectal cancer. He is a member of the Editorial Board of the Journal of Clinical Oncology, The Annals of Surgical Oncology, Surgical Oncology and Cancer Chemotherapy and Pharmacology. In 2001, he was appointed Editor of the Surgical Oncology Clinics of North America. He has been a member of several NIH Study Sections in the field of gastro-intestinal cancer and is presently Chair of the Colorectal Committee of the National Surgical Adjuvant Breast and Bowel Project Cooperative Group. He is a member of numerous professional societies, including the Society of University Surgeons and the American Surgical Association.