Tumor ADC value predicts outcome and yields refined prognostication in uterine cervical cancer

Pelvic MRI is essential for evaluating local and regional tumor extent in uterine cervical cancer (CC). Tumor microstructure captured by diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) markers may be closely linked to prognosis in CC.Purpose To explore whether primary tumor ADC markers predict survival in CC.Material and methods CC patients (n = 179) diagnosed during 2009-2020 with MRI-assessed primary maximum tumor_size ≥ 2 cm were included in this retrospective single-center study. Two radiologists read all MRIs independently, measuring mean tumor ADC values in manually drawn regions of interest (ROIs) and mean tumor ADC (tumor_ADCmean) from five measurements for the two readers was used. ADC from ROIs in the myometrium (myometrium_ADC), cervical stroma (cervix_ADC), and bladder (bladder_ADC) were used to calculate ADC ratios. ADC markers were explored in relation to the International Federation of Gynecology and Obstetrics (FIGO) (2018) stage, disease-specific survival (DSS), and recurrence/progression-free survival (RPFS).Results Inter-reader agreement for all ADC measurements was high (ICC:0.59-0.79). Low tumor_ADCmean predicted advanced FIGO stage (P = 0.04) and reduced DSS (hazard ratio (HR): 0.96, P < 0.001; AIC: 441). Myometrium_ADC/tumor_ADCmean yielded the best Cox regression fit (AIC = 430) among all tumor ADC markers. Patients with high myometrium_ADC/tumor_ADCmean had significantly reduced 5-year DSS for FIGO stage I, II, and III (P = 0.01, 0.004, and 0.02, respectively) and tended to the same for FIGO IV (P = 0.22).Conclusion Low tumor_ADCmean predicted reduced DSS in CC. High myometrium_ADC/tumor_ADCmean was the strongest ADC predictor of poor DSS and a marker of high-risk phenotype independent of FIGO stage.