Computed tomography-based tumour volume as a predictor of outcome in laryngeal cancer: results of the phase 3 ARCON trial.

Retrospective studies indicate that larger tumour volume is a strong prognostic indicator for poor tumour control after (chemo)radiotherapy for laryngeal cancer. The impact of tumour volume on the outcome of patients treated within a prospective study comparing accelerated radiotherapy (AR)±carbogen breathing and nicotinamide (ARCON) was investigated. Of 345 patients with cT2-4 laryngeal cancer, pre-treatment computed tomography (CT) scans of 270 patients were available for tumour volume calculation. Contouring of the primary tumour and involved lymph nodes was reviewed by one experienced head and neck radiation oncologist. Kaplan-Meier plots were used for analysis of outcome. Of 137 AR and 133 ARCON patients, 57 and 80 versus 56 and 77 patients had glottic and supraglottic tumours, respectively. A correlation between primary tumour volume and T-stage was observed (Rs=.51, P<.01). In both treatment arms no correlation was detected between the primary tumour volume and local control (LC), regional control (RC) and metastasis-free survival (MFS). A strong correlation between total nodal volume and N-stage was found (Rs=.93, P<.01). Both in the AR and ARCON groups total nodal volume was not associated with poorer RC rate. However, based on individual lymph node analyses, nodal control was in favour of ARCON, irrespective of volume (P<.01). Neither primary tumour volume, nor total nodal volume is a prognostic factor for patients with cT2-4 laryngeal cancer treated with accelerated radiotherapy±carbogen breathing and nicotinamide. Additional analyses based on individual nodal volumes demonstrate an excellent regional control rate and a significant benefit of ARCON.