Traditional prognostic models for squamous cell carcinoma of the head and neck are based on the TNM staging system. However, there is growing evidence that tumor volume (TV) may be a more accurate predictor of outcome.
To determine whether pathologic TV (pTV) in patients with oropharyngeal squamous cell carcinoma treated surgically is a more significant predictor of outcome compared with pathologic tumor (pT) stage.
Design, Setting, and Participants
Review of patients whose treatment was managed between January 1, 1985, and December 2005 at a US tertiary referral cancer center. The participants included 159 patients who had undergone primary surgery for oropharyngeal squamous cell carcinoma and had 3 dimensions reported on histopathologic testing.
Main Outcomes and Measures
The pTV was calculated as the product of the 3 dimensions expressed in cubic centimeters. For comparison of pT stage with pTV in outcome prediction, concordance indexes were generated using the bootstrap method (n = 1000) to quantify the predictive accuracy of recurrence and survival outcomes. Concordance indexes were then compared and a significant difference was considered when P < .05.
The median age of the patients was 59 years (range, 22-84 years) and 106 were male (67%). Sites of the tumors were base of the tongue (86 patients [54%]), tonsil (48 [30%]), soft palate (24 [15%]), and posterior pharyngeal wall (1 [1%]). The median follow-up time was 64 months (range, 1-272 months). The median tumor volume was 6.8 cm3 (range, 0.1-162.5 cm3). Pathologic TV was a significant predictor of disease-specific mortality. Unlike pT stage, pTV was a significant predictor of local recurrence, regional recurrence, and distant recurrence. Comparison of concordance indexes showed that pTV was a significantly better predictor of disease-specific mortality, local recurrence, and distant recurrence (all P < .05).
Conclusions and Relevance
Pathologic TV outperforms pT stage in the prediction of outcome following surgical treatment of oropharyngeal cancer. Tumor volume should be considered in the design of prospective surgical trials.