The University of Tennessee Graduate School of Medicine, Knoxville

The Department of Surgery

Mark A. Casillas, Jr., MD

Associate Professor
Division of General Surgery

Clinical Focus

Colon and Rectal Surgery; Neoplasms of the Colon, Rectum, and Anus; Inflammatory Bowel Disease; Benign Diseases of the Anorectum; Minimally Invasive Surgery; Robotic Colon and Rectal Surgery; Single Incision Laparoscopy; Transanal Endoscopic Microsurgery

Research Focus

Advances in Minimally Invasive Surgery
Advances in Robotic Colorectal Surgical Outcomes


Graduate School
University of Alabama at Birmingham, Birmingham, AL

Medical School
University of Alabama School of Medicine, Birmingham, AL

General Surgery, Brown University Medical School, Providence, RI

General Surgery, St. Joseph Mercy Hospital, Ann Arbor, MI

Colon and Rectal Surgery, Indiana University School of Medicine, Indianapolis, IN


American Board of Surgery
American Board of Colon and Rectal Surgery

Professional Affiliations

American Society of Colon and Rectal Surgeons, Fellow
American College of Surgeons, Fellow
Society of American Gastrointestinal and Endoscopic Surgeons

Current Publications

Russ AJ, Casillas MA.
Gut microbiota and colorectal surgery: Impact on postoperative complications. Clinics in Colon and Rectal Surgery. 2016 Sep;29(3):253-7.

Giesler DM, Casillas MA, Wilson DD, Nodit L.
The painful diversity of proctitis in the modern era. The American Surgeon. 2015 Nov;81(12):e408-e409(2).

Current Presentations

Lee S, Russ A, Casillas M. Laparoscopic transanal minimally invasive surgery (L-tamis) vs robotic tamis (R-tamis): Short-term outcomes and costs of a prospective comparative study Presented at 16th World Congress of Endoscopic Surgery; 2018 Apr 11-14; Seattle, WA.

Johnson M, Casillas MA, Orucevic A. Adenosquamous carcinoma of the anus: An uncommon malignancy presenting a treatment challenge. Presented at Southeastern Surgical Congress; 2018 Feb 10-13; Tampa, FL.

Bhat S, Cavalea A, Alexander M, Casillas MA, Russ AJ. Combined endoscopic and laparoscopic surgery (CELS) offers improved patient outcomes versus Laparoscopic Colectomy (LC) for endoscopically unresectable Colorectal Neoplasms. Presented at American Society of Colon & Rectal Surgeons Tripartite Meeting; 2017 Jun 10-14; Seattle, WA.

Beierle SP, McLoughlin J, Heidel RE, Casillas M, Russ AJ. Colorectal cancer outcome disparities increase with distance from treating facility. Presented at Academic Surgical Congress; 2017 Feb 7-9; Las Vegas, NV.

Abraham MP, Russ A, Casillas M. Effectiveness of the ligation of intersphincteric fistula tract (LIFT) with biologic mesh interposition in the treatment of fistula-in-ano. Presented at Southeastern Surgical Congress Annual Scientific Meeting; 2016 Feb 20-23; Atlanta, GA.

Abraham MP, Russ AJ, Casillas MS. Transanal minimally invasive surgery (TAMIS) for local excision of rectal neoplasms. Presented at Southeastern Surgical Congress Annual Scientific Meeting; 2016 Feb 20-23; Atlanta, GA.


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