- Causes: Precancerous polyps, particularly adenomatous polyps, are commonly caused by genetic mutations in the cells lining the colon or rectum. Risk factors include older age, family history of polyps or colorectal cancer, inflammatory bowel disease, smoking, and a diet high in fat and low in fiber .
- Presentation: Precancerous polyps usually do not cause symptoms. However, larger polyps or those located in certain areas of the colon or rectum may cause bleeding, change in bowel habits, abdominal pain, or iron deficiency anemia.
- Investigation: Diagnosis of precancerous polyps typically involves screening tests such as colonoscopy, sigmoidoscopy, or virtual colonoscopy (CT colonography) to visualize the colon and rectum and detect any abnormal growths. Biopsy during these procedures allows for the examination of tissue under a microscope to confirm if the polyp is precancerous.
- Diagnosis: Precancerous polyps are diagnosed based on the histopathological examination of biopsy samples obtained during colonoscopy or other screening procedures. Pathologists look for dysplastic changes in the polyp tissue, indicating a higher risk of cancer development.
- Treatment: The primary treatment for precancerous polyps is their complete removal during colonoscopy or surgery. This procedure, known as polypectomy, reduces the risk of colorectal cancer development. Regular surveillance colonoscopies may be recommended to monitor for any new polyps and remove them promptly.
Hyperplastic polyps
A polyp is a general term used for any growth that might be benign. A precancerous polyp by itself is not malignant but if left untreated can become cancerous. It is very common for adults to have polyps in their colon. Precancerous lesions can usually be surgically extracted to avoid cancer. There are two types of polyps hyperplastic polyps and adenomatous polyps.
Hyperplastic polyps are benign and non-cancerous growths. They are small and usually found in the rectum and are not cancerous. Similarly hyperplastic polyps can also be found in the right side of the colon. These polyps pose a risk of cancer. These are treated as precancerous lesions and removed to prevent the spread of cancer.
Adenomatous polyps
Adenomatous polyps are precancerous polyps which cannot be left untreated. These are usually found in the inside lining of the colon and have high potential of becoming cancerous if not removed. Adenomatous polyps are of two types’ tubular adenomas and villous adenomas. Tubular adenomas are common and can become villous adenomas which are cancerous. Villous adenomas are serious and have a very high risk of becoming cancerous. People having villous adenomas have to be screened frequently for colon cancer.
Some polyps with abnormal cells are also called dysplasia. They can be high grade or low grade dyplasia depending on the severity of them turning into cancer.
Stages of a precancerous polyp progressing to cancer
- Genetic factors
- Diet high in fat
- Low intake of fruits and vegetables
- Cigarette smoking
- Sedentary lifestyle with no physical activity
- Obesity
Precancerous Polyps symptoms
The symptoms mentioned below are that of precancerous symptoms of colorectal cancer.
- Diarrhea and constipation
- Bowel obstruction due to a large adenoma
- Protrusion of a polyp through the anus
- Abdominal pain
- Blood in stools
- Decrease in amount of stools expelled
Diagnosis
Medical history and physical exam
The individual is examined for a personal and family history of inflammatory bowel disease, colorectal cancer and hereditary non-polyposis carcinoma. A digital rectal examination (DRE) checks for abnormalities in the rectum or prostate.
Virtual colonoscopy
This is a CT scan which creates images of the colon without inserting an endoscope.
CT scan
It presents three dimensional and cross section images of the organs and is useful to check the spread of cancer to other body parts.
Biopsy
The CT scan helps to guide the needle to perform a biopsy and presence of precancerous cells in a tumor. The suspected tissues are removed and examined under the microscope for malignancy.
Blood chemistry tests
Urea and liver enzymes tests help measure chemicals in the blood and the level at which the colorectal cancer is staged. Higher levels of chemicals are indicative of the cancer having spread to the kidney and liver.
Flexible sigmoidoscopy and colonoscopy
Both tests enable to view the lining of the rectum and colon, respectively for the presence of polyps in the area. If they are found, they are removed and biopsied.
Precancerous Polyps treatment
small polyps can be left alone and can be observed periodically. Large polyps (> 1cm) will require endoscopic removal.