The colon or large intestine is the final part of the intestine. It is shaped like a tube and its interior is lined with a mucous membrane made up of cells. When one of these cells becomes malignant and multiplies uncontrollably, colon cancer develops.

This malignant tumour can grow locally (invading the layers of the wall of the gastrointestinal tract and can reach the organs contained in the abdomen), by lymphatic spread to the lymph nodes or by haematogenous spread (through the blood, preferably to the liver, lung, bone and brain).

If the tumour is detected early, it is curable in more than 90% of cases. For this reason, early detection is vital, as it is a common cancer. 80% of cases are sporadic and 20% are genetically influenced.

The surgery aims to remove:

• Tumour with sufficiently wide margins
• The main arterial and venous vessels supplying the intestinal segment in which the tumour is located
• Regional lymph nodes

Resection can be performed conventionally or laparoscopically, with a smaller incision and a quicker postoperative period. At present, laparoscopic treatment should be considered as the first choice.

Types of surgery:

• Right hemicolectomy (tumour in the cecum or ascending colon)
• Left hemicolectomy (tumour in the descending colon or sigma)
• Segmental colectomies (tumours in the transverse colon or splenic flexure)

After removal of the tumour, it must be analysed and, depending on its characteristics, chemotherapy treatment may be necessary as an adjunct to surgery.

Colon tumour with metastasis

Depending on the stage of the disease, the patient may or may not require chemotherapy treatment. Chemotherapy can mainly be administered intravenously or orally, although there are other forms of administration.

Its administration can be:

• Neoadjuvant treatmentis the administration of chemotherapy prior to possible surgery. The aim is to reduce the size of the tumour and thus facilitate surgery.
• Adjuvant treatmentChemotherapy: is the administration of chemotherapy after surgical resection. The aim is to eliminate possible microscopic disease and to prevent recurrence of the disease.
• Palliative treatmentis the administration of treatment in a palliative manner. The intention is to reduce the burden of the disease and thus to provide clinical benefit.

Occasionally, there are patients with disseminated disease in the liver or lung who respond well to treatment and subsequent intervention is possible.