Recent advances in diagnosis and treatment of colorectal T1 carcinoma

Colorectal T1 tumors (submucosally invasive carcinoma) have special characteristics in terms of pathology, diagnosis, and treatment. The clinicopathologic features of T1 tumors are reviewed.

Incidence of T1 tumors was approximately 10 percent, and the percentage of node metastasis was 10 to 11 percent, whereas hepatic metastasis was <1 percent. Macroscopically they were divided into three types: polypoid, ulcerating, and flat. The ulcerating type was divided into two subgroups: polypoid growth and nonpolypoid growth based on the histologic appearance of resected specimens. The tools for detecting T1 tumors were fecal occult blood test and colonoscopy, and magnifying colonoscopy and chromography facilitate more precise diagnosis. Ultrasonography also was useful for the correct diagnosis of the depth of cancer invasion. Most polypoid and some flat T1 tumors were safely treated by polypectomy or endoscopic mucosal resection alone; however, when resected specimens contained risk factors for metastasis, such as deep invasion (sm2, sm3) and vessel invasion, additional surgery was necessary for cure. For rectal T1 tumors, the most appropriate procedure should be carefully selected from several therapeutic options to preserve anal function.

The management of colorectal T1 tumors should be determined according to the types of macroscopic appearances. The risk of node metastasis could be predicted based on risk factors that were characterized by the level of cancer invasion and the presence or absence of vessel invasion. Minimally invasive treatment should be chosen for colorectal T1 tumors.