Tumor perfusion rate determined noninvasively by dynamic computed tomography predicts outcome in head-and-neck cancer after radiotherapy

Purpose: To investigate the value of CT-determined tumor perfusion as a predictive factor of local and regional failure and cause-specific survival in head-and-neck cancer treated by radiotherapy. Methods and Materials: In 105 patients, the perfusion of a primary head-and-neck squamous cell carcinoma was estimated using dynamic CT. A contrast agent bolus was rapidly injected i.v., while during the first pass a dynamic data acquisition was performed at the level of the largest axial tumor surface. The perfusion in the selected tumor region of interest was calculated by dividing the slope of the tumor-time density curve by the maximal value in arterial density. Primary and nodal tumor volume was calculated from the CT images. All patients were treated by radiotherapy with curative intent; in 15 patients, adjuvant concomitant chemotherapy was administered. Mean follow-up time was 2.2 years. Actuarial (life-table) statistical analysis was done; multivariate analysis was performed using the Cox proportional hazards model. Results: When the patients were stratified according to the median perfusion value (83.5 mL/min/100 g), those with the lower perfusion rate had a significantly higher local failure rate (p < 0.05). In the multivariate analysis, perfusion rate (p = 0.01) and T category (p = 0.03) were found to be the independent predictors of local failure. Perfusion rate had predictive value regarding neither regional control nor cause-specific survival. Conclusion: CT-determined tumor perfusion rate was found to be an independent predictor of local outcome in irradiated head-and-neck cancer. The results of this study confirm the hypothesis that less-perfused tumors respond poorly to radiotherapy.