John H. Marks, MD, FACS, FASCRS, is Chief of the Section of Colorectal Surgery for Main Line Health System and Professor with the Lankenau Institute for Medical Research at Lankenau Hospital in Wynnewood, Pennsylvania. Dr. Marks also directs a colorectal research team and a Minimally Invasive Colorectal Surgery and Advanced Rectal Cancer Management Fellowship.

Dr. Marks' research and educational programs focus largely on sphincter preservation surgery for rectal cancer after neoadjuvant therapy, laparoscopic colorectal surgery, transanal endoscopic microsurgery with full thickness local excision for neoadjuvant-treated rectal cancer, and quality of life following surgery and inflammatory bowel disease.

In Dr. Marks' rigorous effort to promote research and education in the areas of minimally invasive laparoscopic colorectal surgery, sphincter preservation, and the enhancement of the quality of life of the colorectal disease patient, he presents and publishes widely.

Dr. Marks currently serves as President of the Northeastern Society of Colon & Rectal Surgeons, Vice President of the International Congress of Laparoscopic Colorectal Surgery, and Treasurer of the Pennsylvania Society of Colorectal Surgeons.