Colorectal Surgeon Dr. Julio Garcia-Aguilar, MD, PhD (seated) with nurse Kieran Kelleher BSN-RN. Dr. Garcia-Aguilar and the colorectal service at MSK are experts at the watch and wait approach to rectal cancer treatment, which can preserve a patient's quality of life by avoiding surgical removal of the rectum.
There’s an alternative for treating some patients with rectal cancer that makes it possible to avoid surgical removal of the rectum and the related side effects, which can include changes to sexual function and fertility and the possibility of a permanent ostomy bag — a pouch attached outside the body to collect waste.
New results from an ongoing study by Memorial Sloan Kettering Cancer Center (MSK), led by colorectal cancer surgeon Julio Garcia-Aguilar, MD, PhD, finds patients can safely avoid rectal surgery.
Dr. Garcia-Aguilar explains, “We call this approach ‘watch-and-wait,’ and we are very confident we are helping patients with tumors that have not spread to other organs enjoy a better quality of life. At MSK, probably half of the people with rectal cancer don’t undergo surgery and so they do not have their rectums removed.”
Standard treatment involves giving chemotherapy and radiation to shrink the tumor, and then surgically removing the rectum in a procedure called a total mesorectal excision.
MSK has been studying the watch-and-wait approach since the early 2000s and has greatly refined who is most likely to benefit. “We have treated many long-term rectal cancer survivors with the watch-and-wait approach,” says Dr. Garcia-Aguilar. “I have patients who come back to see me 10 years or more after we preserved their rectum by not doing surgery. They are very happy and grateful.”
How the Watch-and-Wait Approach Works for Rectal Cancer Treatment
The rectal cancer tumor watch-and-wait approach is used with people who have what are called local tumors, meaning they have not spread outside the rectum to other organs. The treatment begins like standard-of-care therapy, using a combination of chemotherapy and radiation, sometimes called “chemoradiation.”
The patient is then carefully monitored with a variety of tests including MRI and endoscopy — a scope inserted inside the body. “We have patients come every three to four months so we can see if the tumor appears to be gone,” says Dr. Garcia-Aguilar.
“If we can find no evidence of cancer after chemotherapy and radiation,” he continues, “then we hold off surgery. We continue to monitor them for years. If rectal cancer does come back, we operate and surgically remove the rectum.”
For patients who do end up needing surgery, says Dr. Garcia-Aguilar, “the outcome is no worse than if we operated immediately after chemo and radiation. And at least they had a chance to preserve their rectum.”
Why Preserving the Rectum Can Help Rectal Cancer Patients
Long-lasting consequences
Dr. Garcia-Aguilar believes that preserving the rectum when possible is crucial: “Surgery for rectal cancer has long-lasting consequences for patients in terms of quality of life. In many cases, it involves a permanent colostomy”— a bag on the outside of the body that is used to collect waste.
Changed bowel function
“Even when a permanent colostomy is not necessary, surgery changes bowel function, which many people find very inconvenient and uncomfortable,” says Dr. Garcia-Aguilar.
Other risks due to sensitive location of the rectum
The location of the rectum also presents particular challenges. “It’s in a narrow area of the pelvis, close to a lot of organs in both men and women, and there can be damage to sexual and urinary function, as well as fertility for younger patients,” says Dr. Garcia-Aguilar. “Surgery in this area also has risks of infection as well as a painful recovery. This kind of operation can have serious consequences.”
New Research Shows It’s Safe to Watch and Wait Before Surgery To Remove Rectum
Rectal cancer research at MSK and elsewhere shows that watch and wait for localized rectal cancer appears to be just as safe as surgery to remove the rectum. These studies include a new analysis of watch-and-wait outcomes at MSK and other hospitals in the U.S. compared with multiple institutions in Germany. The research was presented in January 2025 at a premier cancer conference, ASCO GI (American Society of Clinical Oncology Gastroenterology).
Dr. Hannah Williams, a gastrointestinal surgeon who is doing a research fellowship with Dr. Garcia-Aguilar, helped lead the research project. It compared 304 patients at hospitals in Germany who underwent surgery immediately after chemo and radiation with 324 patients at MSK and other U.S. institutions who were treated with watch and wait. Both sets of patients had similar stage 2/stage 3 diagnoses.
The analysis found no difference in survival rates after following the patients for more than three years — and nearly half of the MSK patients treated with watch and wait were able to preserve their rectums. Those MSK patients who had tumor growth during watch and wait had very similar experiences to the patients in Germany who had their rectums removed without waiting.
“This is probably the best evidence we are going to have on the safety and benefit of watch and wait,” says Dr. Garcia-Aguilar, because it compared two similar patient populations in real-world conditions.
Weighing the Possible Risks of the Watch-and-Wait Approach in Rectal Cancer Treatment
Dr. Garcia-Aguilar says that MSK is constantly refining who is likely to benefit from watch and wait. “We study many different characteristics, including the size and location of the tumor, and the molecular make-up of the tumor, to try to determine if it’s particularly aggressive. We look at anything that might help us predict how the tumor will respond.”
Dr. Garcia-Aguilar says that patients who appear to be good candidates for watch and wait are counseled “that in 20-25% of patients, the tumor grows back after chemo and radiation, so we need to surgically remove the rectum. There is always that chance. But most of our patients say they want to take the opportunity to preserve their rectum if possible.”
Chris, diagnosed with Stage 2 rectal cancer in his 50s, came to MSK after receiving chemotherapy and radiation near his home in San Francisco.
“Afterwards, I was told I had complete clinical response, meaning the tumor was effectively gone,” says Chris. “I wondered: Do I still need to undergo surgery?”
Chris, who prefers to keep his last name private, says his medical team didn’t offer that approach but knew it was being successfully used at MSK. They helped him connect with Dr. Garcia-Aguilar.
Within days, Chris and his wife, Kim, flew to New York to meet Dr. Garcia-Aguilar, and MSK quickly performed diagnostic tests. The conclusion: Chris was a good candidate for monitoring to see if the tumor regrew, rather than removing his rectum.
“I knew MSK could do everything right and the tumor still might grow back,” says Chris. “But I wanted the chance to treat my cancer and still live life normally, and it’s been successful.”
Watch and Wait and Metastatic Rectal Cancer
The most dangerous form of rectal cancer is metastatic cancer, meaning cancer that spreads to organs outside the rectum. Dr. Garcia-Aguilar is encouraged by research that shows that watch-and-wait patients are probably no more likely to develop metastasis than patients treated with surgery.
He also believes that watch and wait probably has little influence on the chance of a local cancer turning metastatic. “I tell patients we can never be 100% sure cancer hasn’t spread. But scientific studies and our clinical experience indicate that metastasis usually happens early in the biology of cancer — often before it’s even diagnosed.”
The point, he says, is that metastasis can happen with any treatment approach, because the metastatic cancer cells exist early in the disease. “So we counsel patients that watch and wait has some risks that are very difficult to measure. But we believe that the benefits of the strategy outweigh the risk.”
Other Ways MSK Preserves Quality of Life for Rectal Cancer Patients
Dr. Garcia-Aguilar points out that watch and wait is just one of the innovative approaches to improving outcomes for people facing rectal cancer — including those who are not good candidates for watch and wait. These include:
- A new approach to the sequencing of chemotherapy, developed by gastrointestinal oncologist Deb Schrag, MD, MPH, Chair of the Department of Medicine. For people who do need surgery, this approach may mean they do not need to undergo radiation, which can help preserve fertility in women as well as improve quality of life for men through decreased urinary and sexual side effects.
- An innovative surgical technique that preserves a patient’s ability to carry a child — called a uterine transposition, the procedure helps patients who must undergo radiation for rectal cancer to preserve their fertility. For one family, this approach made it possible to have another child.
- Expertise at robotic-assisted surgery, which can help speed recovery after surgery, reducing pain and other complications, as well as increasing precision.
- A small but heralded clinical trial that used immunotherapy alone to treat rectal cancer in a subset of patients with tumors that have a specific mutation. Every single participant in the trial — which now includes more than 40 people — saw their tumor completely disappear without the use of surgery, radiation, or chemotherapy. “This clinical trial has opened the door to new ways of treating rectal cancer, and we are investigating if this approach might work for people whose tumors do not have this specific mutation,” says Dr. Garcia-Aguilar.
For Chris, MSK’s focus on innovation and preserving quality of life for people facing rectal cancer has made all the difference. “MSK is just the best, from experts like Dr. Garcia-Aguilar to all the nurses and other staff.” Chris is also immensely grateful to his wife, Kim, who accompanied him on every cross-country trip to MSK and has been his rock.
And he has advice for anyone facing early-stage rectal cancer. “If you can, consider MSK. Find out whether you are a good candidate for watch and wait. It’s not easy to go through all the scans to see if the cancer is still gone. But there is nobody better than MSK.”