Primary Tumor Volume Is an Important Predictor of Clinical Outcomes Among Patients With Locally Advanced Squamous Cell Cancer of the Head and Neck Treated With Definitive Chemoradiotherapy

Purpose: The tumor volume has been established as a significant predictor of outcomes among patients with head-and-neck cancer undergoing radiotherapy alone. The present study attempted to add to the existing data on tumor volume as a prognostic factor among patients undergoing chemoradiotherapy. Methods and Materials: A total of 78 patients who had undergone definitive chemoradiotherapy for Stage III-IV squamous cell cancer of the hypopharynx, oropharynx, and larynx were identified. The primary tumor volumes were calculated from the treatment planning computed tomography scans, and these were correlated to the survival and tumor control data obtained from the retrospective analysis. Results: The interval to progression correlated with the primary tumor volume (p = .007). The critical cutoff point for the tumor volume was identified as 35 cm3, and patients with a tumor volume <35 cm3 had a significantly better prognosis than those with a tumor volume >35 cm3 at 5 years (43% vs. 71%, p = .010). Longer survival was also correlated with smaller primary tumor volumes (p = .022). Similarly, patients with a primary tumor volume <35 cm3 had a better prognosis in terms of both progression-free survival (61% vs. 33%, p = .004) and overall survival (84% vs. 41%, p = < .001). On multivariate analysis, the primary tumor volume was the best predictor of recurrence (hazard ratio 4.7, 95% confidence interval 1.9–11.6; p = .001) and survival (hazard ratio 10.0, 95% confidence interval 2.9–35.1; p = < .001). In contrast, the T stage and N stage were not significant factors. Analysis of variance revealed that tumors with locoregional failure were on average 21.6 cm3 larger than tumors without locoregional failure (p = .028) and 27.1-cm3 larger than tumors that recurred as distant metastases (p = .020). Conclusion: The results of our study have shown that the primary tumor volume is a significant prognostic factor in patients with advanced cancer of the head and neck undergoing definitive chemoradiotherapy and correlated with the treatment outcomes better than the T or N stage.