The impact of primary tumor volume on local control for oropharyngeal squamous cell carcinoma treated with radiotherapy

BACKGROUND: A study was needed to determine the effect of primary tumor volume on local control of oropharyngeal carcinoma treated with radiation therapy, with or without induction chemotherapy. METHODS: Between July 1983 and April 1995, 114 patients with T2-T4 squamous cell carcinoma of the oropharynx were treated for cure with radiation therapy, with or without induction chemotherapy, and had a pretreatment CT scan available for retrospective review. All scans were reviewed by a single radiologist (A. A. M.) to determine the tumor volume of the primary lesion. Volume was measured with a computer digitizer for each CT slice showing the primary lesion. RESULTS: A large variation in tumor volume within a given T stage was found. Multivariate analysis demonstrated T stage to be the most significant factor affecting local control. Tumor volume marginally influenced local control (p =.10). CONCLUSIONS: Primary tumor volume varies significantly within a given T stage and has a marginal impact on the likelihood of local control after radiotherapy.