Computed Tomographic Volumetric Analysis as a Predictor of Local Control in Laryngeal Cancers Treated with Conventional Radiotherapy

Abstract

There is still controversy regarding the appropriate management of large T2 and T3 laryngeal cancers, with some investigators finding little correlation between the current TNM staging system and tumour control following external beam radiotherapy. To establish the utility of computed tomography (CT)-determined tumour volume as a predictor of local control of moderately advanced (T2 and T3) squamous cell carcinoma of the larynx. A retrospective chart review and CT volumetric analysis were performed on 47 patients who were treated for T2 or T3 laryngeal squamous cell carcinoma with radiotherapy alone at the London Regional Cancer Centre between 1995 and 2000. Of these 47 patients, there were 30 with glottic tumours and 17 with supraglottic tumours. Forty-two males and five females were included in the analysis, with ages ranging from 40 to 84 years. Each patient's CT scan was redigitized, and the tumours were outlined by the chief investigator and by a head and neck radiologist using anatomy modelling software. Patient demographics, tumour characteristics, and tumour stage were analyzed, with local failure rates described and related to the variables through univariate and multivariate analyses. Tumour size ranged from 0.15 to 16.64 cm3, with a mean volume of 3.5 cm3. The local recurrence rate in this group of patients was 40% (19/47). Local control was correlated on multivariate analysis to tumour size for all patients combined (> 3 cm3 vs < 3 cm3; p = .003) and for glottic tumours alone (> 1 cm3 vs < 1 cm3; p = .001). A correlation was also demonstrated on multivariate analysis between local control and overall stage (p = .023), patient age (p = .029), and hypopharyngeal involvement (p = .032). There is a significant and independent relationship between CT-determined tumour volume and local recurrence in moderately advanced squamous cell carcinoma of the larynx treated with conventional radiotherapy. Based on these results and those of similar studies, CT should therefore become a routine part of the staging system for T2 tumours and above.