Tumor volume as a prognostic factor in oropharyngeal squamous cell carcinoma treated with primary radiotherapy

Objectives/Hypothesis: Tumor volume has been demonstrated to play a prognostic role in many head and neck cancers. The purpose of this study was to conduct an institutional review analyzing the correlation between tumor volume and locoregional control of oropharyngeal squamous cell cancer treated with primary radiotherapy. Study Design: Retrospective institutional chart analysis. Methods: Seventy‐nine patients from 1991 to 2005 with primary T1 to T4 oropharyngeal squamous cell carcinoma (base of tongue, n = 31; soft palate, n = 1; tonsils, n = 47) were treated with primary radiotherapy. Tumor volumes were measured from pretreatment computerized tomography scans by two observers. Three‐dimensional tumor volumes were calculated using a computer digitizer for each computed tomography slice showing the primary lesion. Survival analysis, using the methods of Kaplan and Meier, was performed to assess whether tumor volume, Tumor, Node, Metastasis classification, tumor stage, or location were associated with locoregional failure. Results: Tumor volume did not significantly correlate with locoregional failure (observer 1, P = .6244; observer 2, P = .5612). There was a high interobserver correlation (r = 0.98970). Univariate analysis did, however, demonstrate a significant difference in locoregional failure between T4 tumors and all other T stages (T1 vs. T4, P = .0107; T2 vs. T4, P = .0004; T3 vs. T4, P = .0155). Nodal status, tumor stage, and location did not significantly correlate with locoregional failure rate. Conclusions: Tumor volume does not appear to play a significant role in predicting locoregional recurrence for patients with primary squamous cell cancer of the oropharynx treated with primary radiotherapy. However, T4 status was predictive of poor locoregional control.