Colon cancer screening

It is the second most frequent type of cancer in women after breast cancer and the third in men after lung and cancer. It usually appears between 65 and 75 years of age and in 90% of cases it is a curable neoplasm. From screening, which consists of a series of tests and scans, it is possible to detect and remove precancerous polyps to prevent the development of the malignant tumor or to detect it as soon as possible.

80% of them are sporadic and only a fifth have a genetic influence, with two syndromes that are usually related to this neoplasm, familial adenomatous polyposis and Lynch syndrome or hereditary non-polyposis colorectal cancer. Patients with these diseases must undergo stricter control than the rest of the population, given the greater probability of suffering from colon cancer if they suffer from these diseases.

The main risk factors for sporadic colon cancer are

• Age, with 90% of these cases appearing over 50 years of age.
• Family history, the risk being higher the lower the age of the affected family member, the degree of kinship and the greater the number of family members with a history of colon cancer.
• The diet, with an excess of consumption of red meat, refined sugars and animal fats, to the detriment of foods rich in fiber, folic acid, minerals, vitamins and omega-3 acid.
• Inflammatory bowel diseases (ulcerative colitis and Crohn's disease).
• Alcohol consumption.
• The smoking habit.

Colon cancer often settles on polyps, which are benign lesions that grow on the surface of the lining of the large intestine. 5% of them can become a malignant tumor. It can take between two and three years for a polyp to measure more than one centimeter and from 7 to 10 years to degenerate into cancer, that is, they are slow-growing tumors, hence the importance of being able to detect them in their earliest stages.

The objective of colon cancer screening is to detect and remove precancerous polyps to prevent the development of the malignant tumor, or to detect it as early as possible to maximize the patient's chances of survival. It is estimated that, detected early, 9 out of 10 colon cancers are fully curable.

What is colon cancer screening?

Screening consists of a series of examinations and tests that are applied to people without symptoms or signs of colon cancer but who have a certain risk of suffering from it. The tests used for cancer screening must be sensitive and specific enough to detect the highest number of polyps and carcinomas with the fewest false diagnoses. They must be safe, comfortable and accessible for the general population, as well as cost-effective, that is, they must be less expensive than that derived from the treatment of patients with colon cancer. The tests that have been shown to meet these requirements are:

• Detection of occult blood in feces (DSOH): it is a very simple technique that allows to evaluate if there is blood in the stool that is not seen with the naked eye. Quantitative techniques were used using a reagent, guaiac, but current immunological tests detect more cases, they only require a stool sample and do not require a prior dietary restriction to perform them. It can be carried out by the person at home and then deliver the sample to be taken to the laboratory.
• Flexible sigmoidoscopy: allows the observation of the interior of the last 60 centimeters of the colon, where 4 out of 5 colon cancers are detected, and its use has reduced its incidence by 20% thanks to the detection of premalignant lesions.
• : somewhat more annoying and often performed under sedation, it allows the observation of the entire colon, as well as the taking of biopsies and the extraction of polyps, as well as flexible sigmoidoscopy.

Colon cancer screening is aimed at healthy people at medium risk, those over 50 years of age with no personal or family history of colon cancer or inflammatory bowel disease, and at high risk, those with a personal or family history of polyps or colon cancer or having inflammatory bowel disease.

The tests to be carried out would be ...

In medium-risk patients, annual DSOH and / or sigmoidoscopy every 5 years, or colonoscopy every 10 years. In general, the DSOH is usually performed and if it is positive, the other tests are performed.

In high-risk patients with a family history:

• If there are 2 or more first-degree relatives, or a single first-degree relative diagnosed under the age of 60, a colonoscopy will be performed every 5 years starting at age 40.
• If it is a single first-degree relative diagnosed over 60 years of age or 2 or more second-degree relatives, the same protocol will be carried out as in medium-risk patients but starting at 40 years of age.
• If it is a single second-degree relative or one or more third-degree relatives, the same protocol will be applied as in medium-risk patients, starting the screening at 50 years of age.

Screening is therefore essential to diagnose pre-cancer lesions and correct them, as well as to detect it in its earliest stages if it has already occurred and to maximize the chances of cure. Likewise, in addition to screening techniques, we can help prevent colon cancer through certain practices such as:

• Reduce the consumption of refined sugars, animal fats and red meat in the diet.
• Boost your fiber intake with fruits, vegetables and legumes, as well as white meat (especially blue) and whole grains.
• Reduce alcohol consumption as much as possible.
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• Drink plenty of water.
• Do moderate and regular physical activity.
• Avoid being overweight.