A study on screening of postoperative chemotherapy beneficial populations in stage II colorectal cancer based on diffusion weighted imaging and 18F-fluorodeoxyglucose positron emission tomography/computed tomography.

BACKGROUND: Stage II colorectal cancer (CRC) shows marked prognostic heterogeneity, yet existing single serum or imaging markers are insufficient for reliable high‑risk patient stratification. This study aimed to investigate the value of diffusion-weighted imaging (DWI), fluorine-18fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and serum carcinoembryonic antigen (CEA) for evaluating high‑risk status in stage II colorectal cancer. Both DWI and 18F‑FDG PET/CT could independently identify high‑risk patients, and their combination with CEA further improved predictive performance. This multimodal strategy integrating imaging and serum biomarkers offers a non‑invasive tool to assist individualized risk‑stratified clinical management for stage II colorectal cancer. METHODS: A total of 106 patients with pathologically confirmed CRC were retrospectively enrolled and divided into high-risk stage II and non-high-risk stage II groups according to high-risk factors. Clinical data were collected, and apparent diffusion coefficient (ADC) values and maximum standardized uptake value (SUVmax) of lesions were measured in both groups. The consistency of each parameter was assessed using the intraclass correlation coefficient (ICC). Independent-samples t-test or Mann-Whitney U test was adopted for inter-group comparison of continuous variables. Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic efficacy of each parameter, and the area under the curve (AUC) was calculated. The optimal cutoff value, corresponding sensitivity, and specificity were determined according to the Youden index. Binary logistic regression analysis was used to combine ADC value, SUVmax, and carcinoembryonic antigen (CEA). The Delong test was applied to compare AUC values between the combined model and single parameters. Correlations between ADC value and SUVmax were analyzed using Pearson correlation (for normally distributed data) or Spearman correlation (for non-normally distributed data). RESULTS: ADC values were significantly lower in the high-risk stage II CRC group than in the non-high-risk group (P<0.05), while SUVmax and CEA levels were significantly higher (P<0.05). The combined model of ADC value, SUVmax, and CEA showed better diagnostic performance than any single parameter (P<0.05). A strong negative correlation between SUVmax and ADC value was observed in both the high-risk group r=-0.638 and the non-high-risk group r=-0.777. CONCLUSIONS: The combination of DWI, 18F-FDG PET/CT, and CEA is significantly superior to single modalities in evaluating the benefit of postoperative chemotherapy in CRC patients, and can provide clinical benefit for patients.