Pre-radiation Therapy Tumor Volume as a Predictor of Local Control in Squamous Cell Carcinoma of the Supraglottic Larynx: A 30-Year Experience

Abstract

To examine the utility of pretreatment CT in predicting local control (LC) in patients with squamous cell carcinoma (SCC) of the supraglottic larynx treated with primary radiation therapy (RT). 167 patients treated with primary RT for supraglottic larynx SCC between 1983 and 2013 were reviewed. Patients had received pretreatment diagnostic CT imaging of the larynx and neck with intravenous contrast from which the primary tumor volume was delineated. The mean dose was 74 Gy; 20% received concurrent chemotherapy. LC, larynx function at last follow-up, and RT complications were recorded. Tumor volume was evaluated with respect to outcome. Median age, 61 years. Mean follow-up, 96 months. Of these, 43% had T1-T2, 46% had T3, and 11% had T4 disease; 49% had N0 disease. Median tumor volume, 5.1cm3 (0.4-188 cm3). The 10-year LC for the entire patient population was 78.9%. LC at 5 and 10 years was stratified by tumor volume: 0-4.9 cm3, 5-8.9 cm3, and 9 cm3 and greater. LC by tumor volume among all patients at 10 years were as follows: 0-4.9 cm3, 90.8%; 5-8.9 cm3, 67.3%; and 9 cm3 and greater, 69.4%. LC with preserved larynx function by tumor volume at 10 years was as follows: 0-4.9 cm3, 76.7%; 5-8.9 cm3, 61.5%; and 9 cm3 and greater, 53.4% LC and LC with preserved larynx function was significantly different between primary tumor volume groups (P < .001). On multivariate analysis, primary tumor volume was the only significant predictor of LC and LC with preserved larynx function (P < .005). T stage, N stage, pre-RT larynx dysfunction, chemotherapy, and RT dose did not significantly influence outcome. Six patients developed soft-tissue necrosis; 2 suffered fatal carotid blowouts. Patients with grade 5 complications were treated with concomitant chemotherapy. Four patients required total laryngectomy for a non-functional larynx; 14 required permanent tracheostomy or gastrostomy tube. Pretreatment primary tumor volume helps identify patients most likely to experience LC with primary RT alone or combined chemoradiation. LC for supraglottic larynx SCC is optimal if the primary tumor volume is <5.0cm3.