Development and internal validation of a nomogram to predict colorectal cancer risk in patients with diverticulitis

Usman, M, Correa, E ORCID: 0000-0002-5122-4384, Chung, WY, Farazi, SN, Baronos, K, Samarakoon, L and Kadri, SR (2026) Development and internal validation of a nomogram to predict colorectal cancer risk in patients with diverticulitis. International journal of colorectal disease. ISSN 0179-1958

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Abstract

Aim
Diverticulitis, considered a benign condition, has emerging evidence linking it to colorectal cancer (CRC). Current guidelines lack standardised risk stratification tools to guide post-diverticulitis surveillance. This study aims to create and validate a nomogram to predict CRC risk in patients with diverticulitis.

Method
This retrospective cohort study included 1546 patients diagnosed with diverticulitis at a UK tertiary hospital between January 2021 and December 2023. Patients aged ≥ 18 years who underwent endoscopic assessment following a diverticulitis episode were included. A logistic regression model with L2 regularisation and balanced class weights (C = 0.1) was developed to predict a binary outcome: high CRC risk (histologically confirmed cancer) versus low/moderate risk (no cancer), designed to guide referral for flexible sigmoidoscopy (FS).

Results
The mean age of the cohort was 69.2 years, with near-equal sex distribution. CRC was identified in 42 patients (2.7%). Significant predictors of high CRC risk included older age, male sex, and CT-detected colonic wall thickening, whereas abdominal pain, PR bleeding, and diverticulosis were associated with lower risk. The model achieved a cross-validated mean AUC of 0.736 (95% CI 0.661–0.811) and full-sample AUC of 0.784. At the Youden-optimal threshold (0.523), sensitivity was 72.1% and specificity 73.8%.

Conclusion
We developed and internally validated a nomogram to predict CRC risk in patients with diverticulitis, using a binary classification to guide FS referral. The tool demonstrated robust discriminative ability and could reduce unnecessary colonoscopies while prioritising high-risk patients for timely evaluation. Unlike existing CRC risk models targeting asymptomatic individuals, our nomogram is tailored to diverticulitis patients. External validation in multi-centre cohorts is required before adoption into routine clinical practice.

Item Type:	Article
Uncontrolled Keywords:	Colorectal cancer; Diverticulitis; Nomogram; 32 Biomedical and Clinical Sciences; 3202 Clinical Sciences; 3211 Oncology and Carcinogenesis; Aging; Prevention; Clinical Research; Patient Safety; Colo-Rectal Cancer; Digestive Diseases; Women's Health; Cancer; 4.2 Evaluation of markers and technologies; 4.1 Discovery and preclinical testing of markers and technologies; Cancer; 1103 Clinical Sciences; Gastroenterology & Hepatology; 3202 Clinical sciences
Subjects:	Q Science > QA Mathematics > QA75 Electronic computers. Computer science R Medicine > RC Internal medicine R Medicine > RC Internal medicine > RC0254 Neoplasms. Tumors. Oncology (including Cancer)
Divisions:	Computer Science and Mathematics
Publisher:	Springer
Date of acceptance:	10 June 2026
Date of first compliant Open Access:	2 September 2026
Date Deposited:	02 Sep 2026 08:48
Last Modified:	02 Sep 2026 08:48
DOI or ID number:	10.1007/s00384-026-05181-z
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29283

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