Rectal cancer starts in the last part of the large intestine, just above the anus. Although it is often grouped with colon cancer, it is treated very differently, because the rectum sits deep in the pelvis, close to the nerves that control the bladder and sexual function and the muscles that control the bowel. It is also becoming more common in people under 50. Treatment has changed dramatically in the past few years, and many people can now keep their rectum and avoid surgery altogether. This article explains the tests, the newest treatments, and the integrative research.
The Tests That Decide Treatment
Pelvic MRI shows exactly how deeply the cancer has grown and whether lymph nodes are involved, which guides every decision that follows.
Mismatch repair (MMR) testing is the single most important test. About 5 to 10 percent of rectal cancers are mismatch repair-deficient, and for them immunotherapy alone can make the cancer disappear.
Tumor sequencing and ctDNA. For advanced disease, RAS, BRAF and HER2 testing guide targeted treatment, and blood tests for tumor DNA can show whether cancer remains after treatment. See our articles on tumor DNA and RNA sequencing and ctDNA liquid biopsy.
Immunotherapy Alone: The Cancer Disappeared in Every Patient
At Memorial Sloan Kettering Cancer Center, people with mismatch repair-deficient rectal cancer that had not spread were given six months of the immunotherapy drug dostarlimab alone, with no chemotherapy, radiation or surgery. In the first 12 patients, published in 2022, the cancer disappeared in every one.1 In the 2025 update in the New England Journal of Medicine, all 49 patients with rectal cancer had a complete clinical response, and almost all were able to avoid surgery, keeping their rectum and normal bowel function.2 In July 2026, the international AZUR-1 trial confirmed these results across many countries.3 In October 2026, the FDA approved dostarlimab (Jemperli) for mismatch repair-deficient, locally advanced rectal cancer, making this approach available as a standard treatment in the United States. See our article on ESMO 2026 highlights.
Total Neoadjuvant Therapy
For most rectal cancers, which are mismatch repair-proficient, the standard is now to give all chemotherapy and radiation before surgery, called total neoadjuvant therapy.
The Dutch-Swedish RAPIDO trial. Short-course radiation followed by chemotherapy before surgery reduced the rate of the cancer spreading or returning to 23.7 percent at three years, compared with 30.4 percent with standard chemoradiation.4
The French PRODIGE 23 trial. Giving FOLFIRINOX chemotherapy before chemoradiation improved three-year disease-free survival to 76 percent, from 69 percent, and later improved overall survival.5
Watch and Wait: Keeping the Rectum
When the tumor disappears completely after treatment, close monitoring with MRI and endoscopy can replace surgery. In the American OPRA trial, about half of patients treated with total neoadjuvant therapy kept their rectum.6 The International Watch and Wait Database, led from Maastricht in the Netherlands, followed 880 people who chose monitoring. About one in four had the tumor regrow, nearly always within two years, and most of them could still have successful surgery, with 85 percent alive at five years.7
Metastatic Rectal Cancer
When rectal cancer has spread, it is treated much like metastatic colon cancer, guided by RAS, BRAF, HER2 and mismatch repair testing, and spread limited to the liver or lungs can sometimes be removed. See our article on colon cancer.
Integrative Research in Rectal Cancer
Aspirin, from Sweden and the Nordic countries. The ALASCCA trial, which included people with rectal and colon cancer, found that low-dose aspirin after surgery roughly halved recurrence in cancers with a change in the PI3K growth pathway (Martling and colleagues, New England Journal of Medicine, 2025). Tumor testing shows who may benefit. See our article on cancer driver pathways.
Probiotics during radiation, from Italy. Radiation to the pelvis often causes diarrhea. In an Italian randomized, placebo-controlled trial of 490 people receiving pelvic radiation, including for rectal cancer, those who took a high-potency probiotic had diarrhea less often, 31.6 percent compared with 51.8 percent, and far less severe diarrhea (Delia and colleagues, World Journal of Gastroenterology, 2007).
These are some of the natural and integrative options studied in rectal cancer, and others have promising research as well. Which may fit your situation depends on your tumor testing, your current treatment and possible drug interactions. In a consultation, Dr. Silver, MD, educates you on these options and the research behind them. Request a consultation.
How Cancer Expert MD Helps
Cancer Expert MD provides education and consultation for people with every type and stage of cancer, and specializes in Stage IV and metastatic cancer. Our guide to what to do when treatment stops working explains re-testing and the next steps, and our book, The New Reality of Cancer, covers testing and treatment across all cancers.
Frequently Asked Questions
Can rectal cancer be treated without surgery?
For many people, yes. Mismatch repair-deficient rectal cancer disappeared with immunotherapy alone in every patient in the Memorial Sloan Kettering trial, and others whose tumor disappears after chemotherapy and radiation can be closely monitored instead of having surgery.
What is the most important test in rectal cancer?
Mismatch repair testing of the tumor, because mismatch repair-deficient cancers respond extraordinarily well to immunotherapy.
What is watch and wait?
When the tumor disappears after treatment, regular MRI and endoscopy replace surgery. In the Dutch-led international database, most people who chose it kept their rectum, and those whose tumor regrew could usually still have successful surgery.
Is rectal cancer increasing in young people?
Yes. Rectal bleeding, a change in bowel habits or unexplained weight loss should be checked at any age.
About the author. Dr. Silver, MD, graduated from Temple University School of Medicine, trained as an interventional cardiologist, and has practiced medicine for nearly fifty years. A lymphoma survivor of about twenty-five years, he is co-author, with Dr. Lindmeier, DHSc, of The New Reality of Cancer: The Science of Recovery. Read more about Dr. Silver, MD.
Research by Dr. Lindmeier, DHSc, cancer educator and co-author of The New Reality of Cancer.
This article is for general education only and is not individual medical advice. Always consult your own doctor before making any changes to your care.
© 2026 Lovely LYF LLC. All rights reserved. This article draws on the research in The New Reality of Cancer and may not be copied, republished or distributed without written permission.
For more in-depth information on this topic and many others, get our book, The New Reality of Cancer: The Science of Recovery.
More articles on cancer types and all articles.
References
- Cercek A, Lumish M, Sinopoli J, et al. PD-1 blockade in mismatch repair–deficient, locally advanced rectal cancer. New England Journal of Medicine. 2022;386(25):2363–2376.
- Cercek A, et al. Nonoperative management of mismatch repair–deficient tumors. New England Journal of Medicine. 2025.
- Dostarlimab monotherapy in untreated stage II/III dMMR/MSI-H locally advanced rectal cancer (AZUR-1): primary endpoint of sustained clinical complete response met. July 2026.
- Bahadoer RR, Dijkstra EA, van Etten B, et al. Short-course radiotherapy followed by chemotherapy before total mesorectal excision versus preoperative chemoradiotherapy in locally advanced rectal cancer (RAPIDO). The Lancet Oncology. 2021;22(1):29–42.
- Conroy T, Bosset JF, Etienne PL, et al. Neoadjuvant chemotherapy with FOLFIRINOX and preoperative chemoradiotherapy for patients with locally advanced rectal cancer (UNICANCER-PRODIGE 23). The Lancet Oncology. 2021;22(5):702–715.
- Garcia-Aguilar J, Patil S, Gollub MJ, et al. Organ preservation in patients with rectal adenocarcinoma treated with total neoadjuvant therapy (OPRA). Journal of Clinical Oncology. 2022;40(23):2546–2556.
- van der Valk MJM, Hilling DE, Bastiaannet E, et al. Long-term outcomes of clinical complete responders after neoadjuvant treatment for rectal cancer in the International Watch & Wait Database. The Lancet. 2018;391(10139):2537–2545.
This article is for education only. It is not medical advice and does not diagnose or treat any condition. Cancer Expert MD has no financial relationship with any laboratory, drug maker, supplement company, clinic or hospital.
Leave a Reply