Experienced teaching points

Clinical Pearls

Laterally spreading tumors (LSTs) are nonpolypoid colorectal lesions ≥1 cm; their risk of harboring covert invasive cancer is heavily dependent on surface morphology (granular vs. non-granular).
LST non-granular (LST-NG) pseudodepressed type lesions carry the highest risk for covert submucosal cancer, approaching 36%, and warrant aggressive en bloc resection (e.g., ESD) and careful histopathological evaluation.
Granular mixed LSTs (GM-LSTs) located in the rectum that are ≥4 cm carry an absolute risk of 22% for covert cancer, nearly three times higher than GM-LSTs in other colonic locations or of smaller sizes.

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).

LAST-G have a low risk of containing cancer (approx. 10%)

LST-NG have the highest risk for covert cancer (approx one third).

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 (1). 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 (1, 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.

About the authors

Diana L. Dougherty, MD, MPH

Associate Program Director, Gastroenterology Fellowship

Carilion Clinic / Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA

Diana L. Dougherty, MD, MPH, is the Associate Program Director of the Gastroenterology Fellowship at Carilion Clinic and Virginia Tech Carilion School of Medicine in Roanoke, Virginia. She earned her medical degree from Drexel University College of Medicine and completed her internal medicine residency at the National Capital Consortium before joining the Carilion gastroenterology faculty after fellowship training.

Klaus Mönkemüller, MD, PhD, FASGE, FJGES, FESGE

Editor-in-Chief, The Practicing Endoscopist

Professor of Medicine, Carilion Memorial Hospital / Virginia Tech Carilion School of Medicine, Roanoke, Virginia, USA

Klaus Mönkemüller, MD, PhD, FASGE, FJGES, FESGE, is the editor-in-chief of The Practicing Endoscopist and the founder of EndoCollab. He is Professor of Medicine at Virginia Tech Carilion School of Medicine and a practicing endoscopist at Carilion Memorial Hospital in Roanoke, Virginia.

Dr. Mönkemüller has published extensively on endoscopic techniques and devices, with a particular focus on therapeutic endoscopy, foreign body removal, GI bleeding, and the use of caps and accessories in everyday practice. He lectures internationally and has contributed to multiple GI endoscopy textbooks and atlases.

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