
Areas of Expertise
Conditions I Treat
- Colon cancer
- Rectal cancer
- Anal cancer
My Specialties
- Minimally invasive surgery
- Robotic surgery
- Laparoscopic surgery
Get to Know 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.
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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.
A colorectal (KOH-loh-REK-tul) surgeon is a doctor with special training in surgery on the colon and rectum.
- Vice Chair for Faculty Affairs, Department of Surgery
- Stuart H.Q. Quan Chair in Colorectal Surgery
Conditions I Treat
- Colon cancer
- Rectal cancer
- Anal cancer
- Appendiceal (appendix) cancer and conditions
My Specialties
- Minimally invasive surgery
- Robotic surgery
- Laparoscopic surgery
- Nerve-sparing surgery
- Preserving bowel, bladder, and sexual function
- Clinical trials
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
Awards and Honors
- Castle Connolly: America’s Top Doctor (2025)
- Castle Connolly: America’s Top Doctor (2024)
- Top Doctors New York Metro Area, Castle Connolly (2023)
- Castle Connolly: America's Top Doctors (2023)
- Castle Connolly: New York Magazine Top Doctors (2012-2020)
Insurance Information
Understanding your insurance options is an important part of managing your cancer care. We have relationships with many common healthcare providers and plans.
In Network Coverage Type
PPO
In Network Coverage Type
PPO, POS, EPO, HMO
In Network Coverage Type
HMO, PPO
In Network Coverage Type
HMO, EPO PPO, POS
In Network Coverage Type
PPO, POS, EPO, HMO
Offers a qualified health plan from the Health Insurance Marketplace. Call Emblem to learn more.
In Network Coverage Type
PPO, HMO
In Network Coverage Type
PPO
In Network Coverage Type
HMO, EPO
Offers a qualified health plan from the Health Insurance Marketplace. Call Fidelis to learn more.
In Network Coverage Type
EPO, HMO, PPO, POS
Offers a qualified health plan from the Health Insurance Marketplace. Call Healthfirst to learn more.
In Network Coverage Type
HMO
In Network Coverage Type
PPO
In Network Coverage Type
EPO
In Network Coverage Type
EPO
In Network Coverage Type
Federal Government
In Network Coverage Type
HMO
City Employee Health Plans (Gold and Gold Care)
In Network Coverage Type
PPO, POS, EPO, HMO
In Network Coverage Type
State Government
Don't see your carrier or plan? We can help you understand your coverage.
If you don't have health insurance or are worried that your care may not be fully covered, our financial assistance programs may be able to help.
If you have questions about insurance, call us at 646-497-9176.
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Contact and Location
Dr. Weiser sees patients at one location.












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Colleagues
Doctors at Memorial Sloan Kettering work as teams, with specialists from all different areas. This allows us to consider all your needs together, and to give you the best possible care.
Clinical Trials
- Clinical Trials Co-Investigated by Dr. Weiser
- A Phase 2 Study of Botensilimab and Balstilimab Immunotherapy Before Surgery for Rectal Cancer
- A Phase II Study of Dostarlimab Immunotherapy in People with Locally Advanced "Mismatch Repair-Deficient" Rectal Cancer

Memorial Sloan Kettering's doctors and scientists are constantly developing new treatments for cancer. MSK is typically running hundreds of clinical trials at a given time.
You may be able to participate in a clinical trial even if you are new to MSK. Search our online directory to find trial information and see more about who can participate.
Search clinical trialsResearch and Publications
Selected Book Chapters
Weiser MR and Saltz LB. Chapter 44 Adenocarcinoma of the Colon and Rectum. In Scientific American Surgery. 2015
Patel S and Weiser MR. Robotic Rectal Surgery. In Rectal Cancer: Modern Approaches to Treatment (Chang et al, editors) 2016
Pappou M and Weiser MR. Proctectomy. In The ASCRS Textbook of Colon and Rectal Surgery. 2016.
Weiser MR. Robotic Right Hemicolectomy. SAGES Manual. 2017
Pappou M and Weiser MR. Total Mesorectal Excision. In Textbook of Surgical Oncology 2016
Weiser MR. Open, Laparoscopic, and Robotic Right Hemicolectomy for Cancer. Mastery of Surgery. 2017
Fedler S and Weiser MR. Pelvic Exenteration. In Colon and Rectal Surgery: Abdominal Operations 2nd Ed. 2017.
Langan R and Weiser MR. Stage IV Colorectal Cancer. In Clinical Decision Making in Colorectal Surgery, 2nd edition, edited by Dr. Scott Steele, Justin Maykel, and Steven D. Wexner. Springer Science and Business Media. 2017
Weiser MR and Garcia-Aguilar J Basic Principles of the Operative Treatment of Colorectal Cancer In: Yeo CJ, ed. Shackelford’s Surgery of the Alimentary Tract, 8th edition. Elsevier; 2018.
Weiser MR. Perspective on colorectal neoplasms. In Zinner M and Ashley S (ed.), Maingot’s Abdominal Operations, 13th ed., in press. McGraw-Hill, New York.
Kleiman DA, Weiser MR. 2018. Locally advanced rectal cancer. In Hochwald SN and Cance WG (ed.), Complex General Surgical Oncology. Decker, Toronto. https://www.deckerip.com/products/cgso/
Visit PubMed for a full listing of Dr. Weiser’s journal articles. Pubmed is an online index of research papers and other articles from the US National Library of Medicine and the National Institutes of Health.
See all on PubMedPatient Reviews
Your trust is our main concern
We strive to keep reviews trustworthy, honest and fair. Learn more about our patient experience reviews.
4.9 358 reviews
- 4.8 Provider's Explanations Easy to Understand
- 4.8 Trusts Provider with Care
- 4.8 Provider Listened Carefully
- 4.9 Likelihood of Recommending Provider
Dr. Matin Weiser was both an excellent clinician with superb skills, but also a very kind physician with a lovely bedside manner. I could not have had a better experience, both with Dr. Weiser, his staff and the front desk. It is no wonder that MSK is a world-renowned cancer center! I could not be more grateful for the care and attention shown... [patient name removed]
We had first visit today , we come to see Dr. Martin. I am confident with Dr. Martin and his team. he explained treatment choice was reasonable, answer all my questions. I am hand in my mom to his team. All staff were friendly. Thank you all ! God bless !
It was all very good!
Happy to have him as my doctor.
In a word...BELIEVER. That said I should probably explain. Very simply Dr. Weiser was very forthcoming with how he was going to conduct his portion of the surgery. He repeatedly asked both my wife and I if we had any questions or concerns. He fully explained what we needed to do leading up to the surgery. And when we did ask questions he answered them completely without hesitation. That said when he left the room my wife and I felt that we were in exactly the right place with exactly the right surgeon. We became BELIEVERS.
Disclosures
Doctors and faculty members often work with pharmaceutical, device, biotechnology, and life sciences companies, and other organizations outside of MSK, to find safe and effective cancer treatments, to improve patient care, and to educate the health care community.
MSK requires doctors and faculty members to report (“disclose”) the relationships and financial interests they have with external entities. As a commitment to transparency with our community, we make that information available to the public.
Martin R. Weiser discloses the following relationships and financial interests:
-
UptoDate
Intellectual Property Rights; Professional Services and Activities
If you’re a patient at MSK and would like more information about your doctor’s external relationships, please talk with your doctor.
The information published here is a complement to other publicly reported data and is for a specific annual disclosure period. There may be differences between information on this and other public sites as a result of different reporting periods and/or the various ways relationships and financial interests are categorized by organizations that publish such data.
This page and data include information for a specific MSK annual disclosure period (January 1, 2023 through disclosure submission in spring 2024). This data reflects interests that may or may not still exist. This data is updated annually.
Learn more about MSK’s COI policies here. For questions regarding MSK’s COI-related policies and procedures, email MSK’s Compliance Office at ecoi@mskcc.org.