# Optimizing Positron Emission Tomography-Computed Tomography (PET-CT) Use in Colorectal Cancer: Identifying Patients at High Risk of Recurrence

## TL;DR

This study shows that PET-CT scans can help identify stage 3 colorectal cancer patients at high risk of recurrence, but are less useful for earlier stages.

## Contribution

The study identifies a specific SUVmax cutoff for predicting recurrence in stage 3 colorectal cancer.

## Key findings

- In stage 3 CRC, SUVmax of 13.5 predicts recurrence risk (AUC = 0.72).
- High SUVmax and elevated postoperative CEA are linked to worse survival outcomes.
- PET-CT is not effective for predicting recurrence in stage 1 or 2 CRC.

## Abstract

Introduction

This study aimed to evaluate the prognostic significance of preoperative positron emission tomography-computed tomography (PET-CT) in resectable colorectal cancer (CRC), specifically examining the association between standardized uptake value max (SUVmax) and recurrence risk, stratified by pathological stage.

Methods

A retrospective analysis was conducted on 164 CRC patients who underwent PET-CT before curative resection. SUVmax values were assessed for their correlation with overall survival (OS) and recurrence-free survival (RFS). Receiver operating characteristic (ROC) curve analysis was used to determine the SUVmax cutoff for recurrence prediction. Multivariate Cox regression identified independent prognostic factors.

Results

In stage 3 CRC, SUVmax was significantly associated with recurrence risk, with a cutoff of 13.5 (area under the ROC curve (AUC) = 0.72, p = 0.0201), but not in stage 1 or 2 (AUC = 0.54). SUVmax was higher in patients with elevated preoperative carcinoembryonic antigen (CEA) (p = 0.0311), advanced T stage (p < 0.0001), and pathological stage (p < 0.0001). In multivariate analysis, high SUVmax (p = 0.0491) and anastomotic leakage (p = 0.0281) were independent predictors of worse OS, while high SUVmax (p = 0.0201), American Society of Anesthesiologists physical status (ASA-PS) ≥3 (p = 0.0049), and high blood loss (p = 0.0413) were associated with poor RFS in patients with stage 3 CRC. Patients with both high SUVmax and elevated postoperative CEA had significantly worse OS (p = 0.0352) and RFS (p = 0.0075).

Conclusions

Preoperative PET-CT has prognostic value in stage 3 CRC but offers limited utility in earlier stages. Given its cost and restricted predictive capacity, PET-CT should be selectively used for high-risk patients.