Impact of initial tumor volume on radiotherapy outcome in patients with T2 glottic cancer

Abstract

Background: The aim of this study was to quantify the impact of initial tumor volume (TV) on radiotherapy (RT) outcome in patients with T2 glottic cancer. Materials and methods: Initial TV was calculated for 115 consecutive patients with T2 glottic cancer who had been treated with definitive RT alone at a single institution. Results: The results showed strong correlations of TV with 3-year local tumor control (LTC) and disease-free survival (DFS). For TV≤0.7 cm3, 3-year LTC was 83%; for TV 0.7-3.6 cm3 this was 70% and for TV 3.6-17 cm3 44%. Analysis of total dose vs. initial TV showed that larger T2 glottic tumors with a TV of around 5 cm 3 (2-2.5 cm in diameter with 1010 cancer cells) need an extra 6.5 Gy to achieve similar 3-year LTC rates as for small tumors with a TV of 0.5 cm;bsupesup& (~1 cm in diameter with 109 cancer cells). Conclusion: Although classification of tumors according to TV cannot replace TNM staging in daily practice, it could represent a valuable numerical supplement for planning the optimal dose fractionation scheme for individual patients. © 2014 The Author(s).