Parameters that predict local control after definitive radiotherapy for squamous cell carcinoma of the head and neck

To analyze parameters that may influence the likelihood of local control after definitive radiotherapy for head and neck cancer.

Between April 1980 and January 2000, 404 patients were treated with definitive RT alone (358 patients) or combined with adjuvant chemotherapy (46 patients) at our institution and were followed up for 0.25 to 20.25 years (median, 3.5 years.) All living patients were followed up for at least 2 years. All patients had the primary tumor volume calculated on pretreatment CT. End points were local control after RT and local control after RT without a severe late complication. Parameters evaluated in multivariate analyses of these end points included primary site, T stage, primary tumor volume, N stage, histologic differentiation, fractionation schedule, adjuvant chemotherapy, and gender.

The rates of local control and local control without a severe late complication after RT were significantly influenced by primary tumor volume for patients with cancer of the supraglottic larynx and true vocal cord. In contrast, the rates of local control and local control without severe complications for patients with tumors of the oropharynx and hypopharynx were less influenced by tumor volume. Multivariate analysis of the overall population revealed that the only parameter that was significantly related to the probability of local control after RT was T stage. Multivariate analyses stratified by primary site revealed that tumor volume significantly influenced local control for patients with cancers of the supraglottis (p =.0220) and glottis (p =.0042) but not for those with lesions of the tonsillar fossa/posterior tonsillar pillar (p =.0892), base of tongue (p =.9493), anterior tonsillar pillar/soft palate (p =.5909), and hypopharynx (p =.2282).

The most important parameter that has an impact on local control after RT is T stage. Primary tumor volume also significantly influences the probability of local control in cancers of the supraglottis and glottis.