Tubular adenomas of the colon may become cancerous, and those with chorionic component<20% are tubular adenomas, which are often found to have atypical hyperplasia until cancerous, and the cancerous development of adenomas is related to the diameter of the tumor. In addition to the tubular glandular structure, adenomas are often accompanied by papillary component, i.e., chorionic component, which determines the nature of adenomas according to the proportion of the two different structural components in the histology. The proportion of the two different structural components in the histology determines the nature of the adenoma. 20% of the chorionic component are tubular adenomas, 80% are chorionic adenomas, and those between 20% and 80% are mixed adenomas. The possibility of adenomas becoming cancerous exists, but not all adenomas are cancerous. The size of the adenoma is generally considered to have a significant impact on the likelihood of cancer. Adenomas as large as 2 centimeters can have a cancer rate as high as 50%. The amount of choroidal component in the adenoma is another important factor in determining the likelihood of cancer. Broad-based adenomas have a higher rate of carcinoma than do pedunculated adenomas. Patients with colonic tubular adenomas should seek prompt medical attention and standardized treatment under medical supervision.