Adenoma characteristics associated with post-polypectomy proximal colon cancer incidence: a retrospective cohort study

Rhea Harewood,Kate Wooldrage,Amanda J Cross,Christian Von Wagner,Emma C Robbins,James Kinross

doi:10.1038/s41416-022-01719-4

Rhea Harewood, Kate Wooldrage + Show 4 more

Open Access

https://doi.org/10.1038/s41416-022-01719-4

Copy DOI

Abstract

BackgroundColorectal cancer (CRC) screening is less effective at reducing cancer incidence in the proximal colon compared to the distal colorectum. We aimed to identify adenoma characteristics associated with proximal colon cancer (PCC).MethodsEndoscopy and pathology data for patients with ≥1 adenoma detected at baseline colonoscopy were obtained from 17 UK hospitals between 2001 and 2010. Multivariable Cox regression models were used to estimate adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) for PCC, and, for comparison, distal CRC incidence, by adenoma characteristics.ResultsAmong 18,431 patients, 152 and 105 developed PCC and distal CRC, respectively, over a median follow-up of 9.8 years. Baseline adenoma characteristics positively associated with PCC incidence included number (≥3 vs. < 3: aHR 2.10, 95% CI: 1.42–3.09), histology (tubulovillous/villous vs. tubular: aHR 1.61, 95% CI: 1.10–2.35) and location (any proximal vs. distal only: aHR 1.70, 95% CI: 1.20–2.42), for which there was borderline evidence of heterogeneity by subsite (p = 0.055). Adenoma dysplasia (high vs. low grade) was associated with distal CRC (aHR 2.42, 95% CI: 1.44–4.04), but not PCC (p-heterogeneity = 0.023).ConclusionsBaseline adenoma number, histology and proximal location were independently associated with PCC and may be important to identify patients at higher risk for post-polypectomy PCC.

Highlights

Colorectal cancer (CRC) screening is less effective at reducing cancer incidence in the proximal colon compared to the distal colorectum
A retrospective cohort study [10] in a UK population with adenomas detected at baseline colonoscopy reported associations with all-site CRC for adenoma histology and polyp location in low-risk (1–2 small [< 10 mm] adenomas at baseline) and intermediate-risk patients (3–4 small adenomas, or 1–2 adenomas with ≥1 large [≥10 mm] adenoma at baseline) and for adenoma dysplasia in intermediate- and high-risk patients (≥5 small adenomas, or ≥3 adenomas with ≥1 large adenoma at baseline)
235,321 patients were excluded, comprising 174,980 with no adenomas detected, 2859 patients with no baseline colonoscopy, 45,843 patients with CRC or other colonic conditions, 12 with carcinoma in situ diagnosed more than 3 years prior to baseline, 94 with missing examination dates, 6328 without a complete baseline colonoscopy, 3226 with a baseline examination before 2001, 15 with a baseline colonoscopy after 2010 and 1964 with missing data for at least one adenoma characteristic

Summary

Introduction

Colorectal cancer (CRC) screening is less effective at reducing cancer incidence in the proximal colon compared to the distal colorectum. Reductions in incidence have been achieved through colonoscopies to identify and remove adenomas, known precursors, followed by postpolypectomy surveillance colonoscopy to prevent the progression of missed, incompletely resected or de novo adenomas to malignancy These methods have been effective at preventing cancers in the distal colon and rectum, but have demonstrated a weaker protective effect in the proximal colon, with a greater propensity for adenoma recurrence [3,4,5,6] and post-colonoscopy CRC [7,8,9] in this subsite. A multi-centre population-based cohort study in Poland found that among patients with adenomas detected, adenoma size (≥20 mm) and dysplasia were independent risk factors for all-site CRC [13]

Objectives

Methods

Results