Tumor apparent diffusion coefficient as a predictive marker for PD-1 inhibitor outcome in advanced cervical cancer: a retrospective study

Background To investigate whether pre-treatment apparent diffusion coefficient (ADC) values from diffusion-weighted imaging (DWI) predict clinical outcomes in patients with advanced or locally advanced cervical cancer undergoing Programmed Death-1 (PD-1) inhibitor therapy. Despite the growing use of immunotherapy, reliable and non-invasive imaging biomarkers to predict treatment response in cervical cancer are lacking. Methods This retrospective study analyzed 167 cervical cancer patients treated with PD-1 inhibitors at Wuhan Union Hospital between 01/05/2020 and 31/12/2023. The whole tumor ADC (wADC) and substantial tumor ADC (sADC; excluding necrotic, cystic, and vascular regions) were measured on the largest tumor slice. Optimal cut-off values for ADC and inflammatory markers were determined using X-tile software based on overall survival (OS). Progression-free survival (PFS) and OS were analyzed using Kaplan-Meier curves and Cox regression models. Results Lower sADC was associated with significantly worse PFS (hazard ratio [HR] = 1.81; 95% confidence interval [CI]: 1.18-2.80; P = 0.005) and OS (HR = 2.40; 95% CI: 1.36-4.21; P = 0.002), whereas wADC showed no significant prognostic correlation with PFS (HR = 0.64; 95% CI: 0.39-1.06; P = 0.123) and OS (HR = 0.62; 95% CI: 0.32-1.19; P = 0.209). Multivariate Cox regression revealed low-sADC as an independent risk factor for OS (HR = 2.15, 95% CI: 1.14-4.03, P = 0.017) and PFS (HR = 1.70, 95% CI: 1.08-2.67, P = 0.021). Conclusion The substantial tumor ADC (excluding necrotic, cystic, and vascular regions) was associated with prognosis in cervical cancer patients receiving PD-1 inhibitor therapy.