Is tubular adenoma (a type of benign tumor) benign?

From the Guidelines

Tubular adenomas are considered benign tumors, but they have the potential to develop into colorectal cancer if left untreated, and their removal during colonoscopy is a crucial step in preventing this progression. They are a type of polyp commonly found in the colon and rectum, characterized by tubular glandular structures. The risk of malignant transformation depends on several factors, including the size of the adenoma (larger adenomas have a higher risk), the presence of high-grade dysplasia, and whether the adenoma has villous components 1.

Key Characteristics of Tubular Adenomas

• They are the most common type of adenoma, with the majority being smaller than 1 cm in size
• They are considered precancerous lesions because of their potential to develop into colorectal cancer
• The risk of cancer in adenomas less than 1 cm in size is extremely low, but it increases with the size of the adenoma and the presence of villous elements or high-grade dysplasia 1

Importance of Screening and Removal

• Screening colonoscopies are crucial for detecting and removing tubular adenomas before they have a chance to develop into cancer
• The removal of these precancerous lesions during colonoscopy is a safe procedure that can significantly reduce the risk of colorectal cancer
• After removal, patients usually require follow-up colonoscopies at intervals determined by the number, size, and histological features of the adenomas found 1

Clinical Considerations

• The decision to perform colonoscopy and the frequency of follow-up colonoscopies should be individualized based on patient factors, such as age, family history, and the presence of other risk factors for colorectal cancer
• The presence of multiple adenomas, advanced adenomas, or a family history of colorectal cancer may necessitate more frequent screening and surveillance 1

From the Research

Adenoma Tubular Benignity

• Adenomas of the colon are usually benign tumors which carry a tendency for malignancy 2.
• Those with adenomatous structure can develop malignant characteristics in 1.5% to 9.4% of cases 2.
• A case report of a 16-year-old female adolescent with an adenoma of the descending colon revealed a tubular adenoma according to the pathological examination, with signs of mild dysplasia identified 2.
• The study suggests that adenomas, including tubular adenomas, are generally benign but can have the potential to develop malignant characteristics.

Risk of Colorectal Cancer

• The risk of colorectal cancer (CRC) after removal of conventional adenomas and serrated polyps is a concern, with advanced adenomas having a substantially higher risk than non-advanced ones 3, 4.
• The use of surveillance colonoscopy is associated with lower risk of CRC, with a hazard ratio of 0.61 (95% CI 0.39 to 0.98) among patients with high-risk polyps and 0.57 (95% CI 0.35 to 0.92) among low-risk polyps 3.
• Patients with high-risk polyp findings are at higher risk of subsequent CRC and high-risk polyps and may benefit from early surveillance within 3 years 3, 4.

Colonoscopy Surveillance

• Postpolypectomy colonoscopy surveillance aims to prevent colorectal cancer (CRC), with guidelines defining low-risk, intermediate-risk, and high-risk groups 5.
• Evidence supporting the guidelines is limited, but studies suggest that surveillance reduces CRC risk, with a 40%-50% lower incidence with a single surveillance visit than with none 5.
• The effects of surveillance on incidence vary among risk groups, with hazard ratios of 0.56 (95% CI 0.39 to 0.80), 0.59 (0.43 to 0.81), and 0.49 (0.29 to 0.82) in the low-risk, intermediate-risk, and high-risk groups, respectively 5.