Cancer does not develop overnight and there are different “precancerous signs” in every part of the body. Many people have heard that polyps can turn into colorectal cancer, and they can be considered a “precancerous sign” of colorectal cancer. According to some doctors, it takes about 7 to 15 years for a small polyp to turn into colorectal cancer. If polyps are detected early during this period and removed before they become cancerous, the chance of them developing into colorectal cancer can be greatly reduced.

Common polyps can be classified into three types:

1. Hyperplastic polyps: Benign, most common type. According to statistics, half of the people over 50 have hyperplastic polyps. It almost never becomes cancerous and is usually found in the rectum and sigmoid colon.

2. Inflammatory polyps: benign, but resemble cancerous tumours, very vascular and may bleed due to friction. Removal would be recommended.

3. Adenomatous polyps: Prone to malignancy, cancer, and could be present through the entire colorectum. Removal is recommended regardless of size, with ongoing follow-up.

Data show that more than 95% of colorectal cancers are caused by adenomas. However, the colonoscope alone cannot determine whether it is an adenoma or not. When polyps are seen in the bowel wall during colonoscopy, they are recommended to be removed. A biopsy will then be carried out to determine how to follow up. The Hong Kong Government has also launched a bowel cancer screening programme, urging people aged 50 to undergo bowel screening. As the saying has it, prevention is better than cure. Regular check-ups and early detection of polyps, coupled with a good diet and lifestyle habits, can effectively prevent colorectal cancer.