Abstract

After polypectomy, patients with adenomas containing high-grade dysplasia (HGD) are recommended to undergo surveillance at 3 years because of an increased risk of metachronous neoplasia. Although proximal colon cancers are associated with a worse prognosis compared with distal tumors, limited data exist regarding how the laterality of an initial HGD adenoma influences the subsequent risk of colon cancer. This study aimed to analyze the role of the laterality of HGD adenoma on the incidence of metachronous colon cancer.

The Surveillance, Epidemiology, and End Results-Medicare linked database was queried for adults aged ≥65 years who underwent endoscopic polypectomy for HGD adenoma in the proximal or distal colon, defined relative to the splenic flexure (2006-2019). Cox regression assessed the effect of adenoma location on metachronous malignancy. Survival was assessed using a Kaplan-Meier model.

In a cohort of 523 patients, 41% had proximal HGD adenomas. The 10-year cumulative incidence of postpolypectomy colon cancer was 33% for proximal and 8% for distal adenomas (P <.01). The median time to diagnosis of colon cancer was 2.8 years for proximal adenomas compared with 4.1 years for distal adenomas. Proximal HGD location was significantly associated with an increased incidence of metachronous cancer (hazard ratio, 4.19; 95% CI, 1.90-9.26) after adjusting for age and sex. Patients with proximal HGD had worse 10-year overall survival than that of patients with distal adenomas (49% vs 57%).

The proximal location of an HGD adenoma was associated with a 4-fold increased incidence of and a shorter interval to metachronous colon cancer diagnosis. The location of an HGD adenoma may be taken into consideration when determining clinical management and surveillance.

EDRN PI Authors

• Bresalier, Bob

Medline Author List

• Frebault J
• Goffredo P
• Hassan I
• Marmor S
• Mott SL
• Shaukat A
• Troester A
• Weaver L

PubMed ID

Appears In

J Gastrointest Surg, 2026 Aug (issue 8)