Preoperative model predicts lateral lymph node metastasis in rectal cancer

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medRxiv Published April 22, 2026 Medically reviewed April 25, 2026 Study authors: Shen, Q.; Wang, G.; Fu, M.; Yao, K.; Yang, Y.; Zeng, Q.; Guo, Y. DOI ↗ By Dr. Amelia Tan, PhD · Internal Medicine & Chronic Disease

Key Takeaway

Consider this model for preoperative lateral lymph node metastasis risk stratification in rectal cancer, but await external validation before routine use.

In a retrospective cohort of 64 patients undergoing lateral lymph node dissection for rectal cancer, investigators assessed a preoperative clinicoradiological model for predicting pathological lateral lymph node metastasis. The model incorporated MRI-measured lateral lymph node short-axis diameter, dichotomised clinical T stage, dichotomised clinical N stage, and log(CA19-9+1).

Pathological lateral lymph node metastasis was present in 21 of 64 patients (32.8%). The model demonstrated good discrimination for predicting metastasis, with an AUC of 0.914. Bootstrap internal validation yielded an optimism-corrected AUC of 0.887. Calibration was acceptable after optimism correction, with a calibration intercept of -0.127 and a slope of 1.045.

No safety or tolerability data were reported, as this was a diagnostic prediction study without therapeutic intervention. The study was retrospective and relied on internal validation only; external validation is required before routine clinical implementation. The authors note that the model shows potential clinical utility but requires external validation, and that the association is not causation.

In practice, the model may assist individualized risk stratification and treatment planning for preoperative assessment of lateral lymph node metastasis risk in rectal cancer. Clinicians should interpret these findings cautiously pending prospective, external validation.

Study Details

Study typeCohort

Sample sizen = 64

EvidenceLevel 3

PublishedApr 2026

View Original Abstract ↓

Background: Lateral lymph node metastasis (LLNM) is associated with poor prognosis in patients with rectal cancer and may influence the indication for lateral lymph node dissection. Accurate preoperative identification of LLNM remains challenging. This study aimed to develop and internally validate a clinicoradiological model for preoperative prediction of LLNM in rectal cancer. Methods A retrospective cohort of 64 patients undergoing lateral lymph node dissection (LLND) for rectal cancer was analysed; 21 (32.8%) had pathological lateral lymph node metastasis (LLNM). A prespecified preoperative clinicoradiological model was fitted using penalised logistic regression with L2 regularisation (ridge), incorporating MRI-measured lateral lymph node short-axis diameter (LLN-SAD), dichotomised clinical T stage (T3-4 vs T1-2), dichotomised clinical N stage (N+ vs N0), and log(CA19-9+1). Model performance was evaluated using the area under the receiver operating characteristic curve (AUC), calibration analysis, and bootstrap internal validation. Results The model showed good discrimination (AUC 0.914), with an optimism-corrected AUC of 0.887 on bootstrap validation. Calibration remained acceptable after optimism correction (calibration intercept -0.127; slope 1.045). Decision curve analysis suggested net benefit across clinically relevant threshold probabilities, particularly between 0.10 and 0.30. The model was implemented as a web-based calculator to facilitate clinical use. Conclusion This clinicoradiological model showed good discrimination, acceptable calibration, and potential clinical utility for preoperative assessment of LLNM risk in rectal cancer. It may assist individualized risk stratification and treatment planning, although external validation is required before routine clinical implementation.