Screening Colonscopy for early detection of Polyps and Colon Cancer
Colorectal cancers arise from the inner lining of the large intestine. Most of them are “silent“ tumour. They are however preventable and curable if detected early. Hence the importance of screening procedures for the same.
Colon cancers usually begin as a polyp, a term used to describe a growth in the inner surface of the colon. there are two main types of polyps
- Hyperplastic /inflammatory polyps: these are usually harmless and do not lead to cancers unless located in the proximal colon or have a serrated appearance.
- Adenomas / adenomatous polyps: these are gland like growths that develop on the mucous membrane lining of the colon and are often precancerous
The polyps can be single or multiple.
They are usually silent, getting picked up in a screening procedure but may present with varying combinations of the following symptoms:
- Blood in the stool: these individuals can have bleeding while passing stools or it might just mild spotting of blood . Bleeding which is not visible to the naked eye can also occur for years which might lead to anaemia
- Diarrhoea: this can happen when a large polyp secretes fluid into the intestine
- Constipation: this can happen when a large polyp causes obstruction in the intestine
- Pain / nausea / vomiting: sometimes the polyp can drag a part of the intestine into itself, a process called ‘intussesception‘. This may lead to abdominal pain, nausea and vomiting.
Individuals at risk
These individuals are at a higher risk and need to subject themselves to routine screening.
- Age > 50 years
- Smoking / drinking frequently
- Sedentary life style / eating a high fat diet
- Family h/o polyps
- h/o uterine / ovarian cancer before the age of 50
- h/o Crohns disease / ulcerative colitis
- uncontrolled diabetes mellitus
- hereditary disorders such as Lynch syndrome / Gardners syndrome
Screening colonoscopy is done where a camera is attached to a thin flexible tube which is threaded through your anus and your entire colon is screened for the presence of polyps . In case of detection of any polyp the polyp is biopsied or removed and sent for histopathological analysis.
If a polyp is too large then it cannot be removed by colonoscopy and is then removed by minimally invasive laparoscopic surgery.
There has been no absolute consensus arrived at for the time of follow up of patients or the frequency of follow up but the general consensus is that it depends on the findings during the screening colonoscopy. When there are no polyps found in the screening the individual can be screened again after 10 years. Individuals with a positive family history , multiple polyps , increased size of polyp and varied histology need to be screened more often at frequent intervals at the discretion of the treating doctor.
Prevention of polyps
Dietary and lifestyle modifications have been advised for the prevention of polyps. Increased intake of fruits and vegetables, food rich in vit d and calcium has been advised. Cessation of smoking, regular exercise cutting down on consumption of high fat food, red meat and processed food has also been advised.
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