Efficacy and safety of cold snare polypectomy (csp) of intermediate sized colorectal polyps

body: Colorectal neoplasms are divided into three morphological types: depressed-type, flat-type and protruded-type. We aimed to investigate clinical and pathological characteristics and long-term prognosis of depressed-type colorectal neoplasms, considered as “de novo” pathway, which is considered to emerge directly from normal epithelium, not through the adenomatous stage. Method: A total of 37,146 colorectal neoplasms excluding advanced cancers were resected endoscopically or surgically in our center from April 2001 to December 2019. Of these, 1,342 lesions were T1 carcinomas. According to the developmental morphology classification, they were divided into 3 types: 294 lesions (21.9%) were depressed-type, 481 lesions (35.8%) were flat-type and 566 lesions (42.1%) were protruded-type. We analyzed the pathological difference of these lesions. Results and Discussion: Among T1 carcinomas, the rates of vessel invasion were 48%, 22% and 21%, that of poorly differentiated ormucinous adenocarcinomawas 16%, 10% and 14%, that of massively submucosal invasion was 94.5%, 71.3% and 77.5%, and that of tumor budding was 34.5%, 14.8% and 16.9%, respectively. The rates of these pathological factors were significantly higher in depressed-type lesions than other types. On the other hand, the rate of adenomatous component was 5.1%, 56.7% and 51.5%, and the rate of polypoid growth was 13.8%, 57.4% and 96.4% respectively. It was significantly lower in depressed-type lesions, suggesting that they emerge directly from normal epithelium without going through the adenomatous stage. The rates of lymph node metastasis were 8.7%, 3.1% and 10.2%, respectively, in which no significant difference was found in these three types. The rate of distant metastasis or recurrence was 1% (10/ 1,342). Among these 10 cases, 5 cases were depressed-type lesions among which one showed a para-aortic lymph node metastasis and four showed a lung metastasis. Conclusions: Depressed-type colorectal neoplasms contained malignant clinical and pathological characteristics. Detection and precise diagnosis of depressed-type colorectal neoplasms is important in the treatment of colorectal carcinomas. SUNDAY, MAY 23, 2021