Quick Case: Laterally Spreading Tumor LST in Ascending Colon

by Diana Dougherty, MD and Klaus Klaus Mönkemüller, MD, PhD, FASGE, FJGES

Department of Gastroenterology, Carilion Memorial Hospital, Virginia Tech Carilion School of Medicine, Roanoke, USA

Laterally spreading tumors (LSTs) are defined as nonpolypoid lesions ≥1 cm with lateral growth.

LST occasionally harbor cancer. 

The two main categories of LST, based on their surface morphology, are granular (G) and non-granular (NG). 

LST-G have a low risk of containing cancer (about 8%) (1).

LST-NG have the highest risk for covert cancer (about 21%) (1). 

Kobayashi: "The frequency of pathological T1 cancers was the highest at 36% of LST nongranular pseudodepressed type, followed by 14% of LST nongranular flat‐elevated type, 11% of LST granular nodular mixed type, and 3% of LST granular homogenous type lesions" (1).

The subtype of mixed LST with mixed features (GM-LSTs) have been poorly characterized, intermediate risk for covert cancer, about 10%. The risk of cancer on GM-LST varies by size, being twofold higher in lesions ≥4 cm than smaller lesions, and GM-LSTs in the rectum have a threefold higher risk than other locations to harbor covert cancer (2). The absolute risk for covert cancer was highest (22%) if the GM-LST was both rectal and ≥4 cm, compared with 5% to 8% absolute risk for other size and location combinations (2).

References: 

1. Kobayashi K, Tanaka S, Murakami Y, Ishikawa H, Sada M, Oka S, Saito Y, Iishi H, Kudo SE, Ikematsu H, Igarashi M, Saitoh Y, Inoue Y, Hisabe T, Tsuruta O, Sano Y, Yamano H, Shimizu S, Yahagi N, Matsuda K, Nakamura H, Fujii T, Sugihara K; Colorectal Endoscopic Resection Standardization Implementation Working Group of the Japanese Society for Cancer of the Colon and Rectum. Predictors of invasive cancer of large laterally spreading colorectal tumors: A multicenter study in Japan. JGH Open. 2019 Jul 16;4(1):83-89. doi: 10.1002/jgh3.12222. PMID: 32055702; PMCID: PMC7008164.

2. D'Amico F et al. Risk of covert submucosal cancer in patients with granular mixed laterally spreading tumors. Clin Gastroenterol Hepatol 2020 Jul 17; [e-pub]. https://doi.org/10.1016/j.cgh.2020.07.024. 

No COI by DD or KM with any of the companies/utensils or products mentioned in this article.