Accelerated superfractionated radiotherapy with concomitant boost for locally advanced head-and-neck squamous cell carcinomas.
ABSTRACT A growing body of evidence supports the efficacy of accelerated superfractionated radiotherapy with concomitant boost for advanced head-and-neck carcinomas. This study represents a single-institution experience, performed to identify the factors influencing tumor control, survival, and toxicity.
Between 1988 and 1999, 133 patients with primary squamous cell head-and-neck carcinoma underwent accelerated superfractionated radiotherapy using a concomitant boost. The concomitant boost in this regimen was delivered using reduced fields delivered 3 times weekly in a twice-daily schedule during the final phase. The total radiation dose ranged from 64.8 Gy to 76.5 Gy (mean 71.1). Patients were evaluated in follow-up for local control and late toxicity. Multivariate analysis of treatment and patient parameters was performed to evaluate their influence on toxicity, local control, and overall survival.
With a mean follow-up of 37 months, the actuarial overall survival rate for the entire group at 5 years was 24% and the local control rate was 57%. The tumor volume was the most significant predictor of local control, such that each 1-cm(3) increase in volume was associated with a 1% decrease in local control. For patients with tumor volumes </=30 cm(3) vs. >30 cm(3), the 5-year disease-specific survival rate was 52% and 27% (p = 0.004) and locoregional control rate was 76% and 26% (p <0.001), respectively. Seventy-six patients with a minimum of 12 months and median of 39 months toxicity follow-up were studied for late effects. None of these patients experienced Grade 4 or 5 toxicity. The actuarial rate of significant toxicity (Grade III or greater) was 32% at 5 years. Of the toxicities observed, xerostomia (19%) was the most common. Multivariate analysis revealed N stage and dose as independent predictors of Grade 3 effects.
The locoregional control and survival for patients in this institutional experience compare favorably to other published reports. Tumors of the larynx had the best prognosis. Larger volume tumors were associated with significantly lower local control and survival. Significant late effects were related to dose and nodal status.