RECURSIVE PARTITIONING ANALYSIS OF 2105 PATIENTS TREATED IN RADIATION-THERAPY ONCOLOGY GROUP STUDIES OF HEAD AND NECK-CANCER

BACKGROUND. The Radiation Therapy Oncology Group conducts large-scale pro prospective, randomized trials to test new concepts in cancer pati ent care and provide information about pretreatment and treatment fact ors that may influence outcome. METHODS, Recursive partitioning analys is (RPA) was used to examine the data derived from 2105 patients. RPA grouped patients according to the influence of tumor, of host, and of treatment variables on outcome. RESULTS, For survival, the most import ant factor was T classification. For lesions less than T3, the primary tumor was the next most important factor, whereas for T3 and T4 lesio ns the Karnofsky score was the next most predictive factor. Six distin ct groups were formed by RPA, with median survivals ranging from 6.8 t o 151.8 months. For local-regional control, the N classification was t he most important factor. For patients with no adenopathy, T classific ation was the next most important factor, whereas for patients with ad enopathy, the number of treatment fractions was the next most importan t factor. Such analysis created 5 distinct groups. In the most favorab le, the median time to local-regional relapse has not yet been reached . In the least favorable group, fewer than 50% of the patients experie nced complete response at any time following treatment. CONCLUSIONS. R PA clarifies the relative importance and potential interactions of pre treatment and treatment variables and should permit more accurate stra tification of patients in future trials.