A. David McCollum, M.D. specializes in medical oncology and hematology. His clinical and research interests focus on cancers of the gastrointestinal tract, including colon cancer, rectal cancer, esophageal and stomach cancer, and pancreatic cancer.  He is a Diplomate of the American Board of Internal Medicine with subspecialty certifications in hematology and medical oncology. Dr. McCollum served on the Board of Texas Oncology between 2007 and 2010 and is a member of the Scientific Planning Committee of Texas Oncology and the Gastrointestinal Cancers Committee of The US Oncology Network. Dr. McCollum’s academic affiliations have included Instructor of Internal Medicine at U.T. Southwestern Medical School, Dallas, Texas, 1998-1999, and Instructor of Medicine at Harvard Medical School, Boston, Massachusetts, 1999-2002. He served as a member of the Gastrointestinal Cancers Research Committee at Dana Farber/Partners Cancer Care from 2000 through the spring of 2002. Upon joining Texas Oncology, P.A. in 2002, he became a member of The US Oncology Network Gastrointestinal Cancers Research Committee.