Colorectal cancer is one of the commonest cancers of the gastro-intestinal tract. It is the third most common cancer in men (663000 cases, 10.0% of all cancer cases) and the second most common in women (571000 cases, 9.4% of all cancer cases).
Rectum is the terminal part of the small intestine. It helps in holding the faeces like a reservoir. At the time of bowel movement, the rectum pushes the faeces out through the anus.
The treatment of rectal cancer is complicated because of its close proximity to the anus and its critical function. Surgery which is the most critical part of treatment is technically challenging. In any cancer surgery, there are two considerations. Firstly, removal of the involved part with a reasonable margin of tissue around it. (Sometimes, the cancer cells permeate away from the tumour for a few centimetres invisible to the naked eye). Secondly, removal of the regional lymph nodes which carry cancer cells away from the tumour.
The anus which is the external opening of the rectum contains a muscle called the anal sphincter which helps in maintaining continence (control over defecation). The continuous tightness of this sphincter is vital to prevent a person from defecating without control. Otherwise, stool would be coming out of anus all the time. In elderly people and some of those with neurological problems, the sphincter muscle becomes lax and they become “incontinent” i.e they lose control over defecation.
In a rectal tumour which is close to the anus, the surgeon is often in a dilemma about whether to remove the anus or not. If the anus is removed to ensure wide margins, the patient will have to undergo a permanent colostomy. Colostomy is an artificial opening made on the abdominal wall for the colonic content to drain out into a plastic stoma bag. On the other hand, if the surgeon compromises and does not take adequate margin of resection, there is an increased chance of recurrence. So, the surgical oncologist walks a tight rope to balance the two objectives.
Oncologists often advice a patient to go for radiation therapy initially if it will help in achieving a better chance of sphincter preservation surgery. This is called Neo-adjuvant radiotherapy. Though surgery is the most important aspect of localised rectal cancer management. An experienced surgeon who is trained in performing these procedures regularly is very essential to achieve good results in achieving sphincter preservation surgery. Especially, experience in a technique called as Inter-sphincteric resection surgery is essential to achieve the dual goals of sphincter preservation and adequate margins. Another strategy which might help is the “Transanal excision” technique which can be performed in patients with tumours which were initially small and shrink significantly post radiotherapy.
Keypoint : Specially trained experienced surgeon, Intersphincteric resection technique, Neoadjuvant Radiotherapy help in avoiding a permanent colostomy in patients with rectal cancer