Martin R. Weiser, MD

Surgical Oncologist

Vice Chair for Education and Faculty Development, Department of Surgery; Stuart H.Q. Quan Chair in Colorectal Surgery

Conditions Treated

Memorial Sloan Kettering surgical oncologist Martin Weiser
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About Me

As a surgical oncologist, I specialize in treating cancers of the gastrointestinal tract such as colon cancer, rectal cancer, anal cancer, small bowel cancers, and appendiceal cancer. I am skilled at treating primary, metastatic, and recurrent tumors. My expertise in minimally invasive (laparoscopic and robotic) surgery enables me to remove tumors without causing significant trauma to the patient. Whenever possible, I use nerve-sparing surgical techniques that preserve sphincter, bladder, and sexual function.

My clinical research focuses on increasing the accuracy of tumor staging and improving the methods of predicting outcomes following cancer surgery. I monitor and update Memorial Sloan Kettering’s colorectal cancer database, which we use to track patient outcomes and ensure that we are providing the highest quality of care. My laboratory research focuses on understanding the mechanisms underlying tumor spread and metastasis and on targeting those mechanisms in designing effective treatments. This work includes developing new tools to identify and measure tumor DNA in the bloodstream. I am also the surgical lead for the international prospective randomized trial PROSPECT, which is aimed at individualizing rectal cancer treatment in order to improve outcomes and reduce treatment-related toxicity.

In my practice, I emphasize personalized patient care. Physician assistants, nurses, and staff at our clinic pay careful attention to each patient’s particular needs. We also emphasize a team approach and work closely with specialists in radiation oncology, medical oncology, and other services. Members of this multidisciplinary team discuss individual cases at our weekly conferences with the goal of providing the most comprehensive care possible.

I have served as MSK’s Medical Staff President, Chair of the Colorectal Task Group for the Society of Surgical Oncology, Colorectal Track Leader for the Education Committee of the American Society of Clinical Oncology, and Program Chair of the Annual Meeting of the American Society of Colon and Rectal Surgeons. Currently, I serve on the staging committee and the precision medicine committee of the American Joint Committee on Cancer, which works on updating the colorectal cancer staging system used by cancer centers throughout the United States.  

I am a member of the editorial boards of the Journal of Clinical Oncology, Annals of Surgical Oncology, International Journal of Surgery, and Scientific American Surgery, and I serve as the Colorectal Surgery section editor for UpToDate, an online resource for patients and physicians. I often review submitted manuscripts for the New England Journal of Medicine, Science, the Journal of the American Medical Association, and Lancet Oncology. My publications include over 250 research articles, book chapters, reviews, and editorials on a variety of topics, such as laparoscopic and robotic surgery, the biology of colon and rectal cancers, the treatment of rare anorectal tumors, cancer staging, predictors of outcomes following surgery, and the mechanisms of tumor metastasis. I also lecture nationally and internationally on the management of colorectal, anal, and appendiceal cancers and on the latest advances in minimally invasive surgery.

  • Clinical Expertise: Colon and Rectal Cancer Surgery; Minimally Invasive Surgery
  • Awards and Honors: Castle Connolly: New York Magazine Top Doctors (2012-2018)
  • Languages Spoken: English
  • Education: MD, University of Chicago
  • Residencies: General Surgery - Brigham and Women's Hospital
  • Fellowships: Surgical Oncology - Memorial Sloan Kettering Cancer Center; Colon and Rectal Surgery - Mount Sinai Medical Center
  • Board Certifications: Surgery; Colon and Rectal Surgery

My Research

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See Martin R. Weiser’s laboratory
research at Memorial Sloan Kettering.

See My Colleagues


Selected Book Chapters
“Adenocarcinoma of the colon and rectum.” Weiser MR, Saltz LB, Posner MC. In: Shackelford’s Surgery of the Alimentary Tract. 7th ed. Yeo CJ, ed. Philadelphia: WB Saunders; 2012.

“Left hemicolectomy for cancer.” Weiser MR. In: Mastery of Surgery. 6th ed. Fischer JE, ed. Chicago: Lippincott Williams & Wilkins; 2012.

“Endorectal ultrasound for preoperative staging.” Loh B, Weiser MR, Wong WD. In: Intersphincteric Resection of Low Rectal Tumors. Schiessel R, Metzger P, eds. New York: Springer; 2012.

“Rectal cancer.” Kim H, Weiser MR. In: Clinical Scenarios in Surgery: Decision Making and Operative Techniques. Dimick JB, Upchurch GR Jr, Sonnenday CJ. Philadelphia: Lippincott Williams & Wilkins; 2013.

Visit PubMed for a full listing of Martin R. Weiser’s journal articles

Pubmed is an online index of biomedical articles maintained by the U.S. National Library of Medicine and the National Institutes of Health.

Clinical Trials

As home to one of the world’s top cancer research centers, Memorial Sloan Kettering is typically involved in more than 900 clinical trials at a given time. Currently, clinical trials focused on the conditions I treat are enrolling new patients. If you’re interested in joining a clinical trial, click to learn about the trial’s purpose, eligibility criteria, and how to get more information.

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Most major health insurers offer plans that include MSK as one of their in-network providers. If MSK is in-network, it means all our doctors are too. Medicare and New York State Medicaid also provide benefits for care at MSK.

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