Mark Edward Mahan, DO

Mark Mahan, DO, is a board-certified general surgeon specializing in bariatric and foregut surgery. He performs advanced and specialized surgical procedures, including gastric bypass, gastric sleeve, single anastomosis duondenoileal bypass, LINX procedure and revisional bariatric surgery. He also performs many general surgery procedures, including appendix and gallbladder removal, treatment of various types of hernia and benign colorectal and breast diseases. He also treats people for conditions affecting the stomach and gastrointestinal (GI) system, including GERD, hiatal hernia, paraesophageal hernia, achalasia and acid reflux. He has a clinical interest in robotic and laparoscopic surgery, patient quality and safety, resident education and hospital systems utilization.

Dr. Mahan earned his medical degree from New York Institute of Technology College of Osteopathic Medicine in Old Westbury, NY. After medical school, he completed a general surgery residency at Geisinger Wyoming Valley Medical Center in Wilkes-Barre, where he served as chief resident. He followed that with a bariatric and foregut fellowship at Geisinger Medical Center in Danville.

“What I love most about my job is the human interaction it affords me every day,” he says. “It’s the patient I have yet to meet that makes me excited and motivated to not only come to work, but to continually better myself. Every day I am motivated at the prospect of forming new relationships and creating lifelong impact while training the next generation of surgeons.”

Dr. Mahan is an active member of professional societies and organizations, including The American College of Physicians, American Osteopathic Association, American College of Surgeons and Society of American Gastrointestinal and Endoscopic Surgery. He’s also an active member of American Society for Metabolic and Bariatric Surgery, where he serves on the quality improvement and patient safety committee. There, he works with professionals across the country to improve patient safety standards.

He’s an accomplished researcher and presenter. Dr. Mahan is the lead author on one of five manuscripts selected to the Top Papers session presented at the American Society for Metabolic and Bariatric Surgery (ASMBS) 2023 Annual Conference. That paper also won the Top Bariatric Award at the American College of Surgeons Quality and Safety Conference.

“I’m proud of my research focus with over a dozen current publications and works presented at numerous national conferences,” he notes. 

The loss of his mother inspired him to become a physician, he says. “Personal loss and tragedy requiring medical care, specifically surgery, at a young age gave me great perspective and personal motivation to find a career in helping others. This ultimately led me to becoming a surgeon.” He notes that his father’s work ethic and compassion help make him the physician he is today.

Originally from Farmington, CT, Dr. Mahan decided to move to the area to practice medicine after spending summers in the State College area. He says, “I spent portions of my summer with my sister in State College going fishing, visiting Penn’s Cave, eating whoopie pies from the local Amish and of course ice cream from the Penn State Creamery. These special moments led to my love for Pennsylvania and decision to return to settle down with my own family.”

He notes that he’s proud of being asked to stay on as faculty at Geisinger after he completed his residency and fellowship training, enjoying the close interpersonal relationships he’s forged.

In his spare time, he enjoys spending time with his wife and son, visiting family and friends, watching sports and going on outdoor adventures like hiking, fishing and playing golf.