Colon cancer

What is colon cancer?

Colon and rectal cancer is the third most common cancer in terms of frequency in the global population. Colon cancer is the most common cancer in developed countries, in urban areas and among Caucasians. An important goal in the fight against colorectal cancer is early diagnosis, given that the survival of affected patients depends directly on the stage of the disease at the time of diagnosis.

What lesions can cause colon cancer?

Malignant tumours of the colon and rectum are often associated with certain diseases and conditions that are considered premalignant lesions.

The premalignant lesion in most patients with colon cancer is an adenomatous polyp. Therefore, the basis for early diagnosis is careful monitoring of patients who present with this premalignant lesion.

Colonoscopy can detect and remove these polyps.

Complete resection of the polyp logically leads to the disappearance of its premalignant potential. In addition, it may be the definitive treatment for a polyp that has already become malignant if no malignant cells are found at the resection margin.

A patient with an adenomatous polyp in the colon has a 30% to 50% chance of having a second adenoma at the same time. Therefore, it is important to perform a total colonoscopy to rule out the presence of additional polyps. Furthermore, this patient has a 30-40% chance of developing new polyps in the future. Endoscopic screenings are therefore recommended every 2–3 years.

Other precancerous conditions include:

  • Familial adenomatous polyposis, characterised by the presence of more than 100 polyps on the epithelium of the colon. It is hereditary and has a clear malignant potential.
  • Ulcerative colitis increases the risk of colon cancer (especially in patients who have had the disease for more than 10 years and with extensive disease affecting the entire colon). Crohn's disease also increases the risk of colon cancer.
  • Hereditary non-polyposis colorectal cancer, as its name suggests, is a hereditary disorder in which the tumour appears at an early age (< 45 years). It can be associated with other cancers, and there must be at least three affected relatives.

What other factors can influence its onset?

The risk of colon cancer increases significantly after the age of 50, doubling every decade until it peaks at the age of 70.

Dietary factors: Various studies have shown that diets high in fat predispose people to colorectal cancer, while fibre can have a protective effect.

Warning signs

Colon cancer can grow slowly before showing any symptoms, which will vary depending on the location of the tumour.

Iron deficiency anaemia is the main symptom of right-sided colon cancer.

Rectorragia and changes in the depositional rhythm are more common in left-sided and rectal colon cancer.

Current recommendations are: starting at age 50, annual digital rectal exam, annual faecal occult blood test, and rectosigmoidoscopy or colonoscopy every three to five years.