Nivatvongs, Santhat

The earliest invasive carcinoma of colon and rectum is an invasion into the submucosa. For the TNM classification, these lesions are T1 Nx Mx. They present as an adenoma with invasive carcinoma, or a frank carcinoma. Local excision for T1 carcinoma of the rectum can be curative if the lesion is accessible for an adequate excision and if the lesion has not spread to the lymph nodes or distant metastasis. The key to success in local excision is selecting the lesions that have low risk of metastasis.

AbstractPer anal excision is suitable for rectal carcinoma that is <3 cm and has not invaded into the muscular layer of the rectum. The upper margin of the lesion should not be >7 cm from the anal verge. The entire lesion is excised in its full thickness with a 1.5 cm to 2 cm normal margin, using electrocautery. It is important that the specimen is carefully examined by the pathologist for completeness of the excision and grade of the carcinoma. Abdominoperineal resection should be considered in good risk patients if adequate margins cannot be achieved and if the carcinoma is a high pathologic grade.

AbstractAn early colorectal carcinoma is TNM stage T1NxMx. Most early carcinomas of the colon and rectum can be treated by adequate local excision, such as colonoscopic polypectomy and per‐anal excision. If there are adverse risk factors, especially poorly differentiated carcinoma, lymphovascular invasion, or incomplete excision, a radical resection is indicated if there is no contraindication. In the case of a low rectal carcinoma, adjuvant chemoradiation should be considered. Recently a new classification has been developed: sm1 is invasion to the upper one‐third of the submucosa, sm2 is invasion to the middle one‐third, and sm3 is invasion to the lower one‐third. Lesions of sm1 and sm2 have a low risk of local recurrence and lymph node metastasis; local excision is adequate. The sm3 lesions and sm2 flat and depressed types have a high risk of local recurrence and lymph node metastasis; further treatment is indicated.