Clinicopathological features of laterally spreading colorectal tumors and their association with advanced histology and invasiveness: An experience from Honam province of South Korea: A Honam Association for the Study of Intestinal Diseases (HASID)

Background and aims
Laterally spreading colorectal tumors (LSTs) are divided into four subtypes, including homogenous (HG), nodular mixed (NM), flat elevated (FE), and pseudo-depressed (PD), based on their different endoscopic morphologies. The aim of this study was to investigate the clinicopathological significance of LST subtypes and their association with advanced histology.
Methods
We investigated the medical records of consecutive patients with LST who initially underwent endoscopic resection at five university hospitals in Honam province of South Korea between January 2012 and December 2013. A total of 566LST lesions removed via endoscopic procedures were collected retrospectively for data analysis.
Results
The PD, FE, and NM subtypes were more common in the distal colon and the HG subtype in the proximal colon. The PD subtype had the biggest tumor size, followed by the NM subtype. The frequency of adenomatous pit pattern was significantly higher in the HG, NM, and FE subtypes than in the PD subtype. In contrast, the frequency of cancerous pit pattern was significantly higher in the PD subtype than in the other three subtypes. The rate of advanced histology (high-grade dysplasia or carcinoma) among the LSTs was 36.0%. The risk of advanced histology increased in the distal colon compared with the proximal colon. The PD subtype had the highest incidence of villous component, advanced histology,submucosal invasion, and postprocedure perforation among the four subtypes. The distal colon as tumor site, larger tumor size, PD subtype, and villous component were associated with a statistically significant increased risk of advanced histology.
Conclusion
Our results indicate that the location, size, endoscopic subtype, and histologic component of the LSTs are associated with an increased risk of advanced histology. Therefore, these clinicopathological parameters may be useful in selecting therapeutic strategies in the clinical setting.

【背景与目的】
结直肠侧向发育型肿瘤（Laterally Spreading Colorectal Tumors, LSTs）根据内镜下形态特征可分为四种亚型，即均一型（homogenous, HG）、结节混合型（nodular mixed, NM）、扁平隆起型（flat elevated, FE）及假凹陷型（pseudo-depressed, PD）。本研究旨在探讨LST亚型的临床病理意义及其与进展期组织学改变的关联。

【研究方法】
本研究纳入2012年1月至2013年12月期间，韩国湖南地区五所大学附属医院中首次接受内镜下切除术的连续LST患者的病历资料。本研究回顾性收集了共计566例经内镜手术切除的LST病变用于数据分析。

【研究结果】
假凹陷型（PD）、扁平隆起型（FE）及结节混合型（NM）亚型更多见于结肠远端，而均一型（HG）亚型更多见于结肠近端。PD亚型的肿瘤体积最大，其次为NM亚型。腺瘤性隐窝形态的发生率在HG、NM及FE亚型中显著高于PD亚型；与之相反，癌性隐窝形态的发生率在PD亚型中显著高于其余三种亚型。LST病变中进展期组织学改变（高级别异型增生或癌）的发生率为36.0%。与结肠近端相比，结肠远端病变的进展期组织学改变风险更高。在四种亚型中，PD亚型的绒毛状成分占比、进展期组织学改变发生率、黏膜下浸润率及术后穿孔率均最高。肿瘤位于结肠远端、肿瘤体积更大、为PD亚型及存在绒毛状成分，均与进展期组织学改变的风险显著升高具有统计学相关性。

【研究结论】
本研究结果表明，LST的病变部位、体积、内镜亚型及组织学成分均与进展期组织学改变的风险升高相关。因此，这些临床病理参数可用于临床场景中治疗策略的选择。