Mark A. Lewis is an influential voice in gastrointestinal oncology and serves as Director of Gastrointestinal Oncology at Intermountain Healthcare in Murray, Utah. Building a career driven by personal experience, Dr Lewis has become one of the most recognizable faces in oncology. Dr. Lewis was inspired to pursue oncology after his father died of lung cancer. At the start of his oncology training, he was diagnosed with multiple endocrine neoplasia type 1 (MEN-1), a hereditary cancer syndrome that profoundly shaped his clinical perspective.
He frequently talks about his experience informing the oncology community online on practicing oncology through the dual lens of physician and patient. He promotes open dialogue, patient engagement, and public understanding of cancer, mixed with a witty sense of humor and self-humility.
In 2017, he notably live-streamed his Whipple surgery, highlighting the role of transparency and digital platforms in modern oncology. Dr. Lewis’s work reflects a deep commitment to patient-centered care, advocacy, and communication – demonstrating that meaningful oncology practice extends beyond treatment to connection, understanding, and support. If you did not know Dr Lewis until now, you have surely seen the famous meme that belongs to him.
The 100 Most Influential People in Oncology in 2025 recognizes the changemakers in cancer care who have helped shape current practice in oncology and continue to drive innovation and research towards better outcomes, advocacy, philanthropy, leadership, and education. For the many deserving individuals not mentioned in this list, we will continue to acknowledge, honor, and elevate your voices in our daily publications from across the world.
See the full list of The 100 Influential People in Oncology in 2025 and stay tuned for the results of special category nominations to be announced.
