Long-term outcomes after treatment for pedunculated-type T1 colorectal carcinoma: a multicenter retrospective cohort study

The risk for lymph node metastasis and the prognostic significance of pedunculated-type T1 colorectal carcinomas (CRCs) require further study. We aimed to assess the validity of the 2014 Japanese Society for Cancer of the Colon and Rectum (JSCCR) guidelines based on long-term outcomes of pedunculated-type T1 CRCs. In this multicenter retrospective cohort study, we examined 176 patients who underwent resection endoscopically or surgically at 14 institutions between January 1990 and December 2010. Patients meeting the JSCCR curative criteria were defined as "endoscopically curable (e-curable)" and those who did not were "non-e-curable". We evaluated the prognosis of 116 patients (58 e-curable, 58 non-e-curable) who were observed for > 5 years after treatment. Overall incidence of lymph node metastasis was 5 % (4/81; 95 % confidence interval 1.4-12 %: three cases of submucosal invasion depth a parts per thousand yen1000 mu m [stalk invasion] and lymphatic invasion, one case of head invasion and budding grade 2/3). There was no local or metastatic recurrence in the e-curable patients, but six of them died of another cause (observation period, 80 months). There was no local recurrence in the non-e-curable patients; however, distant metastasis was observed in one patient. Death due to the primary disease was not observed in non-e-curable patients, but six of them died of another cause (observation period, 72 months). Our data support the validity of the JSCCR curative criteria for pedunculated-type T1 CRCs. Endoscopic resection cannot be considered curative for pedunculated-type T1 CRC with head invasion alone.