Surgery involves removing all or part of the cancer with an operation. A wide local excision is the most common operation for anorectal melanoma.

Wide local excision

This is the most common operation for anorectal melanoma. The surgeon removes the cancer and a small area (margin) around it. This reduces the risk of any cancer cells being left behind.

The anal muscles are not usually affected. This means you should still be able to control your bowel in the same way as you did before the surgery.

Abdominoperineal resection (APR)

Some people need a bigger operation to remove the cancer. Your doctor may suggest this operation if:

  • you had a local excision but some cancer could not be removed or has come back
  • the tumour is in a difficult area to remove with a local excision
  • the tumour cannot be completely removed by a local excision, and involves structures in the anus or rectum that may cause a loss of bowel control (incontinence).

For an abdominoperineal resection, the surgeon removes all of the anus and rectum and a small part of your colon. They may also remove nearby lymph nodes if the cancer has spread there.

A diagram of abdominoperineal resection (APR)

The illustration shows the large bowel within a body. The colon is shown using a dark yellow colour. The lower end of the colon, the rectum and the anus, that are removed during an abdominoperineal resection, are shown in white.

 

The surgeon closes the hole where the anus was. They make a cut on your abdomen (tummy) and join the end of your bowel to this opening. This is called a stoma or colostomy. Having a stoma means stools (poo) will no longer pass out of the rectum and anus in the usual way. Instead, they will pass out of the stoma into a disposable bag that is worn over it.

A diagram of a stoma or colostomy bag

The illustration shows a person’s trunk from the chest down to the thighs. The diagram shows the position of the bowel within the tummy (abdomen). The stoma, which is where the bowel comes to the surface of the tummy, is on the left-hand side of the tummy. A colostomy bag is shown covering the stoma and hangs down with a sealed end. 

Being told you need a stoma can be distressing. Most people find they get used to the stoma over time. You will get support and advice from a stoma nurse in your hospital.

Anterior resection

Some people have an anterior resection. This is when the surgeon removes the rectum. Sometimes the surgeon will also remove nearby lymph nodes. After the piece of bowel that contains the cancer is removed, the surgeon rejoins the two open ends of bowel. The first diagram shows the part of the bowel that is removed.

A diagram of anterior resection where part of the bowel has been removed

The illustration shows the large bowel within a body. The colon is shown using a dark yellow colour. The lower end of the colon and the rectum, that are removed during an anterior resection, are shown in white.

The second diagram shows how the two ends are joined together.

A diagram an anterior resection, where the two open ends of bowel have been joined together

The illustration shows how the large bowel looks after an anterior resection. It shows how the end of the colon has been joined to the remaining rectum and anus, to replace the rectum that has been removed.

Some people may have a temporary stoma after this operation. This is an opening that is made through the tummy (abdominal) wall and connects the bowel onto the surface of the tummy. Having a stoma means stools (poo) will no longer pass out of the rectum and anus in the usual way. Instead, they will pass out of the stoma into a disposable bag that is worn over it.

People with a temporary stoma will have a second, smaller operation a few months later. This second operation is to close the stoma and rejoin the bowel. It is called a stoma reversal.

Lymph node dissection

Your surgeon may remove lymph nodes as part of the operation if:

  • tests show that the cancer has spread to lymph nodes, or
  • your doctor can feel your lymph nodes.

This is called lymph node dissection. If lymph nodes are removed from the groin, there is a risk of leg swelling. This is called lymphoedema.