How does a polyp turn into cancer?
Most colorectal cancers begin as an adenomatous polyp, a benign growth of the mucosa. Over time, genetic damage accumulates in its cells, and the polyp can become malignant. The risk depends on the size and type of polyp. Removing polyps during a colonoscopy significantly reduces the likelihood of developing cancer.
- Adenomatous polyps are the main precursor to cancer
- Serrated (serrate) formations - the second way of development
- Polyps larger than 10 mm and with a villous structure - increased risk
- Inflammatory bowel disease - cancer due to chronic inflammation
Risk factors
Colorectal cancer is more common after 50 years of age, but in recent years the incidence has been increasing among younger people. Many risk factors are lifestyle related and modifiable.
- Age over 45–50 years
- Colorectal cancer or adenomas in close relatives
- Hereditary syndromes: Lynch syndrome, familial adenomatous polyposis
- Ulcerative colitis and Crohn's disease
- Obesity, inactivity, type 2 diabetes
- Excess red and processed meat, lack of fiber
- Smoking and alcohol
Symptoms
Manifestations depend on the location of the tumor. Cancer of the right side of the colon often presents with anemia and weakness without visible blood in the stool. Tumors of the left half and rectum cause changes in stool, visible blood, false urges, and can lead to intestinal obstruction. Blood in the stool cannot be attributed to hemorrhoids without examination.
- Blood or mucus in the stool
- Changing the usual rhythm and shape of stool
- Abdominal pain and bloating
- Weakness, pallor, anemia
- Weight loss
- False urges, feeling of incomplete emptying
Screening and diagnosis
People at average risk are recommended to start screening at age 45. Two approaches are possible: colonoscopy once every 10 years with a normal result, or an annual immunochemical stool occult blood test with colonoscopy if the result is positive. In case of cancer or adenomas in first-generation relatives, colonoscopy begins earlier. If cancer is confirmed, an examination is performed to determine the stage.
- Colonoscopy with biopsy and polyp removal
- Immunochemical analysis of feces for occult blood
- CT scan of the chest, abdomen and pelvis
- MRI of the pelvis for rectal cancer
- Tumor marker CEA - to monitor treatment
- Molecular genetic study of the tumor
Treatment
Very early cancer in a polyp can be completely removed during colonoscopy. In other cases, the main method is surgical removal of a section of the intestine with lymph nodes, often laparoscopically. For rectal cancer, chemoradiotherapy is often performed before surgery. After surgery, depending on the stage, chemotherapy is prescribed. For metastases, chemotherapy, targeted drugs, immunotherapy are used, and in some cases, metastases in the liver or lungs are also removed. Treatment is planned by a multidisciplinary council.
- Get screened starting at age 45
- If there is blood in the stool, do a colonoscopy rather than treating hemorrhoids at random
- Eat more fiber, limit sausages and red meat
- Maintain a normal weight and physical activity
- Stop smoking and limit alcohol
