EVALUATION OF THE DOSE FOR POSTOPERATIVE RADIATION-THERAPY OF HEAD AND NECK-CANCER - 1ST REPORT OF A PROSPECTIVE RANDOMIZED TRIAL

Purpose: This study was designed to determine in a prospective randomi zed trial the optimal dose of conventionally fractionated postoperativ e radiotherapy for advanced head and neck cancer in relation to clinic al and pathologic risk factors. Methods and Materials: Between January 1983 and March 1991, 302 patients were enrolled on the study. This an alysis is based on the first 240 patients entered through September 19 89, of whom 221 (92%) had AJC Stage III or IV cancers of the oral cavi ty, oropharynx, hypopharynx, or larynx. The patients were stratified b y postulated risk factors and randomized to one of three dose levels r anging between 52.2 Gy and 68.4 Gy, all given in daily doses of 1.8 Gy . Patients receiving > 57.6 Gy had a field reduction at this dose leve l such that boosts were only given to sites of increased risk. Results : The overall crude and actuarial 2-year local-regional recurrence rat es were 25.4% and 26%, respectively. Patients who received a dose of l ess-than-or-equal-to 54 Gy had a significantly higher primary failure rate than those receiving greater-than-or-equal-to 57.6 Gy (p = 0.02). No significant dose response could be demonstrated above 57.6 Gy exce pt for patients with extracapsular nodal disease in the neck in whom t he recurrence rate was significantly higher at 57.6 Gy than at greater -than-or-equal-to 63 Gy. Analysis of prognostic factors predictive of local-regional recurrence showed that the only variable of independent significance was extracapsular nodal disease. However, clusters of tw o or more of the following risk factors were associated with a progres sively increased risk of recurrence: oral cavity primary, mucosal marg ins close or positive, nerve invasion, greater-than-or-equal-to 2 posi tive lymph nodes, largest node > 3 cm, treatment delay greater than 6 weeks, and Zubrod performance status greater-than-or-equal-to 2. Moder ate to severe complications of combined treatment occurred in 7.1% of patients; these were more frequent in patients who received greater-th an-or-equal-to 63 Gy. Conclusion: With daily fractions of 1.8 Gy, a mi nimum tumor dose of 57.6 Gy to the whole operative bed should be deliv ered with a boost of 63 Gy being given to sites of increased risk, esp ecially regions of the neck where extracapsular nodal disease is prese nt. Treatment should be started as soon as possible after surgery. Dos e escalation above 63 Gy at 1.8 Gy per day does not appear to improve the therapeutic ratio.