Timing of MRI for early treatment response prediction of chemoradiotherapy in uterine cervical cancer
To explore the optimal use of MRI including time point to predict early treatment response during definitive chemoradiotherapy in cervical carcinoma. Pilot study including 15 patients with cervical carcinoma stage IIB-IIIB (FIGO 2009) scheduled for chemoradiotherapy. All patients underwent four MRI examinations (at baseline, 3 weeks, 5 weeks, and 12 weeks after treatment start). Maximum tumor size, size change (Δsize), visibility on diffusion-weighted imaging (DWI), apparent diffusion coefficient (ADC) mean and change in ADC (ΔADC) at the different time points were recorded. 7/15 patients relapsed during the study period, referred to as "poor prognosis" (PP) and the remaining 8/15 are referred to as "good prognosis" (GP). At all four time points, the tumors in the PP patients were larger than in the GP patients. Tumor size did change between the time point but this was not significant between the groups. Visible tumor on high b-value DWI reached a sensitivity and specificity for predicting prognostic group being highest at 5 weeks, 83 % (5/6) and 63 % (5/8), respectively. The combination of tumor size at baseline and visible tumor on DWI at 5 weeks, resulted in an area under the curve (AUC) = 0.83. At 12 weeks, no GP patients, but 2/7 PP patients showed visible tumor on DWI. Addition of ADC-values in the analysis did not improve the predictive value at any time point. This pilot study indicates that the tumor size on baseline MRI, combined with tumor visibility on DWI at 5 weeks, may predict outcome of chemoradiotherapy.