Clinicopathological study of superficial-type invasive carcinoma of the colorectum.

We investigated the relationship between histological parameters such as the level of invasion (scanty submucosal invasion, sm-s or massive submucosal invasion, sm-m), histologic grade (presence or absence of grade III carcinoma), lymphatic invasion, venous invasion, budding and lymph node metastasis in 33 lesions of superficial-type invasive colorectal carcinoma. On statistical analysis, there was no definite influence of any histological parameter on lymph node metastasis. None of 6 sm-s lesions showed lymph node metastasis, however, 7 sm-m lesions were found to have lymph node metastasis (25.9%). Whereas only 16.7% (1/6) of the lesions showing sm-s had one or more unfavorable histological parameters, 85.2% (23/27) of the lesions showing sm-m had one or more of unfavorable histological parameters. There was a significant difference between the two types of lesions (p<0.003). Consequently, in the treatment of superficial-type invasive carcinoma, sm-s lesions without unfavorable histological parameters could be radically cured by endoscopic mucosal resection alone.