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This is a plain English summary of an original research article. The views expressed are those of the author(s) and reviewer(s) at the time of publication.

New research suggests that limited surgery is preferable to radical surgery for a rare and aggressive type of cancer called anorectal melanoma. This cancer starts in the anus or rectum (back passage).

In limited surgery (wide local excision or WLE), the cancer and a small area around it is removed. In more radical surgery (abdominoperineal resection or APR), all of the anus and rectum are removed and patients are left needing permanent colostomy bags.

The new research found that the radical APR procedure did not improve survival compared to the more limited WLE. Nor did it reduce further the risk of the cancer re-occurring.

The study suggests that WLE followed by regular check-ups should be the primary treatment strategy for most patients with anorectal melanoma.

What’s the issue?

Anorectal melanoma affects only 0.3 to 1.0 people per million, but the numbers are increasing. It usually occurs in elderly women, and diagnosis often comes late because the cancer can be mistaken for common conditions which are not cancer, such as haemorrhoids, or piles, which are enlarged blood vessels around the rectum and anus.

Radical surgery is a well-established treatment. In APR, the rectum, anus, and a small part of the colon is removed. In recent years a growing number of surgeons and specialists have questioned that approach and argued for the more limited option of WLE.

Patients who have limited surgery are left with a higher quality of life than those who have APR. But it was not clear which strategy offered the best results in terms of survival and the chance of the disease returning.

What’s new?

The systematic review included 27 studies. Many were rated as low-quality because data came from observation of patients’ progress after surgery. They were no high-quality trials in which patients are randomly assigned to receive one type of surgery or the other.

Researchers therefore used a framework designed to make clinical recommendations from low or mixed-quality evidence. They included studies that directly compared APR with WLE for patients with anorectal melanoma.

The results showed:

  • no difference in outcomes between patients who had APR and those who had WLE
  • patients had fewer side effects with WLE
  • APR did not improve survival or make the disease less likely to return.

None of the studies reported how the different operations affected patients’ quality of life.

The researchers concluded that better data is needed on quality of life after APR and WLE to help guide disease management. In the meantime, the researchers suggest that limited surgery, WLE, should be the default option for most patients.

Why is this important?

The results will allow patients and clinicians to directly compare outcomes of the two types of surgery.

The more radical operation has a limited role for some patients. But it leaves patients with life-changing effects and the data suggest it is not always justified on clinical grounds.

Surgeons, dermatologists and GPs may have assumed that the more radical surgery is more effective at clearing the disease and so recommended it to patients.

What’s next?

The study results have already been incorporated into new UK guidelines on the treatment of ano-uro-genital mucosal melanomas, which aim to guide care based on the best scientific evidence.

Published in August 2020, the guidelines say: “APR should not be used routinely as a standard of care. There is no evidence that radical surgery will improve survival.” They add that APR of the rectum can be considered if there is judged to be a significant risk of incontinence from a WLE and that the procedure is fully discussed with the patient.

The study suggests that given the rarity and complexity of ARM, treatment in the UK should be centralised into specialist units. Patients with the disease should have their cases discussed at multidisciplinary tumour board meetings, attended by specialists in anorectal surgery and in melanoma. This could help standardise treatment and increase the numbers of patients entering clinical trials.

New drug treatments for melanoma are becoming available and they may improve outcomes for patients with this cancer. Continuing research will be needed to monitor outcomes as these treatments are used more widely.

This study should reduce the amount of radical surgery performed without proven benefit in anorectal surgery.

You may be interested to read

The full paper: Smith HG, and others. Less is more: a systematic review and meta-analysis of the outcomes of radical versus conservative primary resection in anorectal melanoma. European Journal of Cancer 2020; 135:113-120

The new guidelines: Ano-uro-genital mucosal melanoma UK national guidelines. European Journal of Cancer 2020; 135:22-30

Funding: This research was supported by the NIHR Biomedical Research Centre.

Conflicts of Interest: The study authors declare no conflicts of interest.

Disclaimer: Summaries on NIHR Evidence are not a substitute for professional medical advice. They provide information about research which is funded or supported by the NIHR. Please note that the views expressed are those of the author(s) and reviewer(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

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