COMPARISON BETWEEN NORMAL TISSUE-REACTIONS AND LOCAL TUMOR-CONTROL INHEAD-AND-NECK-CANCER PATIENTS TREATED BY DEFINITIVE RADIOTHERAPY

Purpose: This study was conducted to test for the relationship between tumor and normal tissue radiosensitivity, by comparing local tumor co ntrol to the severity of acute and late normal tissue reactions in hea d and neck cancer patients treated by definitive radiotherapy. Methods and Materials: Two hundred eighty-six patients with head and neck can cer who were treated at the University of Texas M. D. Anderson Cancer Center between 1983 and 1993 were selected for the study. Of these, 12 4 (43%) were treated by a concomitant boost regimen and 162 (57%) by h yperfractionation. All patients had at least 1 year of follow-up. The tumor stage distribution according to the 1992 American Joint Committe e on Cancer (AJCC) staging system was as follows: T1, 3%; T2, 53%; T3, 40%; T4, 4%. The average doses delivered were 71.2 Gy and 76.2 Gy for the concomitant boost and hyperfractionation regimens, respectively, with no significant variation between patients. Acute and late reactio ns were recorded using the Radiation Therapy Oncology Group (RTOG)/Eur opean Organization for Reasearch on Treatment of Cancer (EORTC) gradin g system (0 to 4). The median follow-up period was 38 months (range: 1 2-107 months). The time to local tumor recurrence was analyzed in rela tion to the severity of acute and late reactions expressed as the maxi mum recorded grades, and to the time intensity of acute mucositis, exp ressed as the area under the curve of mucositis grade vs. time. Univar iate and multivariate analyses also included T stage, N stage, and sit e of origin as other prognostic variables, and were carried out using a proportional hazards model. Results: Fifty-four patients (19%) suffe red local failure. T stage was found to significantly influence local control (p = 0.009). There was a nonsignificant trend for higher failu re rates in patients with maximum Grade 1 or 2 vs. those with Grade 3 or 4 acute mucositis (28 and 18%, respectively; p = 0.17). No correlat ion was found between the severity of late reactions and local tumor c ontrol after radiotherapy. Analysis by time intensity of mucositis rev ealed a wide variation between individuals with a nonsignificant trend for higher local failure rates in patients with low mucositis time in tensity scores. Conclusions: These clinical results suggest a possible relationship between normal tissue and tumor radiosensitivity. Howeve r, additional studies with a larger numbers of patients, and using ref ined normal tissue endpoints that incorporate a time function are need ed to fully elucidate this question.