According to research reviewed by Gram Research analysis, removing colon cancer tissue through the anus during robot-assisted surgery was linked to less blood loss, less pain, and faster recovery than the belly method. Among 166 matched patients, the anus group also had fewer incision complications and a shorter hospital stay.
A new retrospective study, reviewed by Gram Research analysis, compared two ways of removing tumors during robot-assisted surgery for sigmoid colon and upper rectal cancer. In one method, surgeons remove the tissue through a small incision in the belly. In the other, they pull it out through the anus, which avoids an extra belly incision. Among 166 well-matched patients treated between 2019 and 2026, the anus method was linked to less blood loss, less pain, fewer incision problems, earlier return of bowel function, and a shorter hospital stay. Cancer removal quality and bowel function at three months looked similar in both groups. Because this was a retrospective review of past records, the researchers say larger, prospective studies are needed before this approach can be recommended broadly.
Key Statistics
A 2026 retrospective cohort study of 254 patients with sigmoid or upper rectal cancer found that removing tissue through the anus during robot-assisted surgery was linked to fewer incision complications and lower pain scores than the belly method.
In a 2026 propensity score-matched analysis of 83 patients per group, those who had anus-based tissue removal left the hospital sooner and had lower inflammation markers on days one, three, and five after surgery.
A 2026 study from the First Affiliated Hospital of Jiangxi Medical College found no difference between the two surgical methods in total operating time, lymph node count, or bowel and anal function at three months.
The Quick Take
- What they studied: Researchers wanted to know whether pulling a removed colon cancer section out through the anus, instead of through a belly incision, leads to a better recovery after robot-assisted surgery.
- Who participated: The study reviewed 254 adults who had robot-assisted surgery for cancer in the sigmoid colon or upper rectum at one hospital in China between January 2019 and January 2026. After matching the two groups for similar characteristics, 83 patients were in each group.
- Key finding: Patients who had the tissue removed through the anus had less blood loss, less pain, fewer incision problems, faster return of bowel function, and a shorter hospital stay. Their inflammation markers were also lower in the first five days after surgery. Surgery length and cancer removal quality were similar.
- What it means for you: If you are facing this type of surgery, this study suggests the anus method may help with recovery for carefully selected patients. Your surgical team can explain whether this approach fits your specific cancer and health situation. This is one hospital’s past experience, so the results may not apply to everyone.
The Research Details
This was a retrospective cohort study, which means the researchers looked back at the medical records of patients who had already been treated. They did not assign patients to a method themselves. Instead, the team compared patients who had the tissue removed through the anus with those who had it removed through a belly incision, based on what their surgeons had chosen at the time.
Because the two groups were not randomly formed, patients in each group could differ in ways that affect recovery, such as age or disease stage. To reduce this problem, the researchers used a statistical technique called propensity score matching. This method pairs patients from each group who have similar starting characteristics, so the comparison is more fair. After matching, 83 patients remained in each group.
The team then tracked short-term results such as surgery time, blood loss, pain scores, blood markers of inflammation, the return of gas and bowel movements, hospital stay length, and complications. They also checked bowel and anal function at three months.
A retrospective design is a practical first step for comparing surgical techniques, especially newer ones. It can show whether a method is worth studying further, using records from many real patients over several years. However, because it looks back at existing records, it cannot prove that one method caused the differences seen. Matching the groups helps, but it cannot account for every hidden difference between patients.
The study followed a recognized statistical method to make the groups more comparable, and it included a reasonable number of patients. The results were published in a peer-reviewed journal. Still, it came from a single hospital, and the surgeons likely had reasons for choosing each method, which may have influenced who received which treatment. Results from a retrospective review are generally considered less reliable than those from a randomized trial, where patients are assigned to groups by chance.
What the Results Show
The most consistent advantages were seen in the anus removal group. Surgeons needed less time to reconnect the bowel after removing the cancer section, and patients lost less blood during surgery. The researchers reported statistically significant differences for both measures.
Patients who had the anus method also recovered their normal activities faster. They got out of bed, passed gas, and started eating soft liquid food sooner than the belly group. These are important milestones, because they signal that the digestive system is starting to work again after surgery.
Recovery signals in the body were also better. Blood levels of C-reactive protein, a general marker of inflammation, were lower on days one, three, and five after surgery in the anus group. Patients in this group also had fewer incision-related complications and lower pain scores, and they left the hospital about a day sooner on average.
Not every outcome showed a difference. Total operating time, the number of lymph nodes removed for examination, whether the cancer was fully removed with clear edges, and bowel and anal function at three months looked similar between the two groups. This suggests that the anus method did not compromise cancer removal in these patients.
The study also looked at how well the bowel and anus worked three months after surgery. Both groups had similar results, which is reassuring because it suggests the anus method did not cause lasting problems with bowel control in the patients studied. Cancer-specific measures, such as the number of lymph nodes examined and whether the tumor edges were clear, were also comparable. These measures matter because they relate to how well the cancer was removed and how accurately doctors can stage the disease.
Natural orifice specimen extraction, often shortened to NOSES, has been studied as a way to avoid an extra abdominal incision. Earlier research on various forms of this approach has generally reported less pain and faster recovery, though results have varied by technique and patient group. This study adds evidence specifically for robot-assisted surgery in sigmoid and upper rectal cancer, a group that has received less direct comparison. Its findings fit with the broader trend toward less invasive methods, but larger studies are still needed to confirm them.
The study was retrospective, so the researchers could not control which patients received which method, and some differences between the groups may have remained even after matching. It was conducted at a single hospital, so results may not match what happens at other centers with different surgeons and routines. Follow-up was short, with most outcomes measured in the early weeks after surgery and bowel and anal function checked only at three months. Longer-term outcomes, such as cancer recurrence and survival, were not reported in the summary. The authors themselves call for larger, multicenter, prospective studies with longer follow-up.
The Bottom Line
Based on this study, the anus removal method appears to be a feasible option for carefully chosen patients with sigmoid or upper rectal cancer who are having robot-assisted surgery. Confidence in the short-term recovery benefits is moderate, since the results are consistent across several measures but come from a retrospective review. Confidence that the approach is safe for long-term cancer outcomes is lower, because those outcomes were not the focus here. Patients should discuss the options with their surgical team rather than requesting a specific method on their own.
Patients being evaluated for sigmoid colon or upper rectal cancer, their families, and colorectal surgeons may find this research relevant. It is most relevant to people whose tumors are suitable for this technique, as determined by their surgical team. People with other types of cancer, or with conditions that make this approach unsuitable, should not assume these results apply to them. Anyone seeking general health advice should consult a qualified healthcare provider.
In this study, the recovery differences appeared within the first few days to weeks after surgery. Patients in the anus removal group left the hospital slightly sooner, and their pain and inflammation levels were lower during the early recovery period. Bowel and anal function were checked at three months and looked similar between groups. Longer-term outcomes, such as cancer control over years, are not yet known from this study.
Frequently Asked Questions
Is removing colon cancer tissue through the anus better than through the belly?
A 2026 retrospective study of 166 matched patients found the anus method was linked to less blood loss, less pain, fewer incision complications, and a shorter hospital stay. Researchers say larger studies are needed before it can be recommended broadly.
How much faster do patients recover after anus-based tissue removal during robot surgery?
In the study, patients who had tissue removed through the anus got out of bed, passed gas, and started soft foods sooner than the belly group. They also left the hospital slightly earlier, though the study did not report exact daily differences in the summary.
Does removing tissue through the anus affect bowel control after cancer surgery?
At three months after surgery, bowel and anal function looked similar between the anus group and the belly group. The study found no significant difference, though longer follow-up is needed to understand lasting effects on bowel control.
Is this surgical method safe for every colon or rectal cancer patient?
No single method suits everyone. The study focused on patients with sigmoid or upper rectal cancer who were carefully selected for the approach. Your surgical team decides which method fits your tumor size, location, and overall health.
Want to Apply This Research?
- After surgery, log your daily pain score on a 0 to 10 scale, the time you first get out of bed, the first time you pass gas, and the first day you eat soft foods. These are the same milestones the study tracked, so they will help you see your own recovery pattern.
- Use the app to set reminders for short walks several times a day once your care team approves it, since early movement was linked to faster recovery in the study. Log each walk so you can see your progress over the first two weeks.
- Continue logging bowel habits, pain levels, and any incision changes such as redness, swelling, or drainage for the first three months, which matches the study’s follow-up window. Share the log with your surgical team at each visit, and report any warning signs such as fever or worsening pain right away. Keep records of your follow-up appointments and cancer screening schedule over the longer term.
This article summarizes a retrospective study of past patient records from a single hospital and is for general information only. It is not medical advice. Surgical choices depend on your cancer type, stage, and overall health, so talk with your oncologist or colorectal surgeon before making any decisions about treatment.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.