Clinicopathological And Endoscopic Treatment Of Laterally Spreading Tumor(LST): A Retrospective Analysis

Objective: To analyze the clinicopathological and endoscopic treatmentof colorectal LST.Methods: Recording and analyzing the age, gender, lesion site,lesion size,morphological classification, histological type, treatment and treatmentresults of the patients with LST.Results:(1) Age and gender：A total of101patients with LST were found,54cases of male,47cases of female. The mean age of patients was62.00士10.51years old.(2) Lesion site：Most LSTs occurred in the rectum(52.47%).Comparedwith LST-NG, LST-G more often occurred in the rectum (P<0.001).(3)Lesion size：The mean size of LST was20.88士10.35mm. The meansize of LST-G was larger than that of LST-NG (P<0.001).Most LST-G werelarger than20mm (76.27%),while LST-NG were smaller than20mm (59.52%)(P<0.001).(4) Histological：The histological of LSTs were tubular adenoma(49.50%) and low grade intraepithelial neoplasia (69.31%).There wassignificant difference between LST-G and LST-NG in histological(P=0.006).LST-G in villous adenoma, villous-tubular adenoma and serrated adenomaaccounted for61.01%, while three in LST-NG accounted for23.81%(P<0.001).(5) Carcinogenesis：The carcinogenesis rate of LST was8.91%,and itwas highest in pseudo-depressed type(16.67%) The lesion size influencedcarcinogenesis(P=0.013)(6) Treatment: A total of65LSTs were treated by EMR,22LSTs were treated by ESD and14LSTs were treated by surgical．ESD group wasassociated with a larger lesion size(P=0.001)，higher en bloc resection(P<0.001),lower recurrence（P=0.001）,longer procedure time(P<0.001).Lesion size was a risk factor of the en bloc resection in EMR group(P=0.005)．Lesion size and en bloc resection were risk factors of EMRrecurrence（Psize=0.006；Pdysplasia=0.048）。.Conclusion:LST is a special tumor, it is closely related to the colorectal cancer.There was significant difference between LST-G and LST-NG. LST-Gs werelarger in diameter, more often occurred in the rectum, more villous inhistological, but LST-NGs, especially pseudo-depressed type, were higherin canceration rate. It is worth of cLIENical attention and research.Endoscopic treatment was safe and feasible for treating LSTs. ESD providedhigher en bloc resection and lower recurrent rate compared to EMR, despitethe longer procedure time．EMR might be a good alternative to ESD for LSTs≤20mm．...