Carcinoma of the nasopharynx treated by radiotherapy alone: Determinants of local and regional control

Purpose: This retrospective study was conducted to review the results of treatment and to identify prognostic factors for local and regional control in a population of 378 patients with nasopharyngeal carcinomas treated in a single institution by radiation therapy alone. Methods and Material: All patients were treated at The University of Texas M.D. Anderson Cancer Center between 1954 and 1992 following a consistent treatment philosophy but with evolving technique. There were 286 males and 92 females with a median age of 52 years (range: 16-86 years). The majority of the patients were Caucasian (282 patients, 75%). Thirty-two patients (8%) had one or more cranial nerve deficits. Three-fourths of the patients presented with AJCC Stage IV disease (T4, N0-3, 118 patients; T1-3, N2-3 164 patients). Histologically, 193 tumors (51%) were squamous cell carcinomas, 154 (41%) lymphoepitheliomas, and 31 (8%) unclassified carcinomas. Average total dose varied with T-stage and ranged from 60.2 to 72.0 Gy. Median follow-up time was 10 years. Results: For the entire population the 5-, 10-, and 20-year actuarial survival rates were 48, 34, and 18%, respectively, with 184 patients (49%) dying of nasopharyngeal cancer. Actuarial control rates at 5, 10, and 20 years were 71, 66, and 66% for the primary site and 84, 83, and 83% for the neck. A total of 100 patients (26%) had local failures and 51 patients (13%) had regional failures with a median time to recurrence of 8.2 months and 13 months, respectively. Advanced T-stage, squamous histology, and presence of cranial nerve deficits were poor prognostic factors for local control in both univariate and multivariate analyses. N-stage and tumor histology were significant factors for neck control. Treatment year, total dose within the ranges used, and duration of treatment did not have any significant effect on local or regional control. The actuarial incidence of Grade 3-5 late complications was 16, 19, and 29% at 5, 10, and 20 years, respectively. Twelve patients (3%) died of treatment-related complications; all but one fatal complication occurred before 1971 and the other in 1976. Conclusions: This study shows very good long-term local and regional control rates for nasopharyngeal carcinomas after definitive radiotherapy and establishes a benchmark for newer treatment strategies. Improvements in treatment technique over the years have dramatically reduced the frequency of severe late complications. Patients with advanced stage tumors and differentiated squamous histology have a relatively poor prognosis when treated with conventional radiotherapy and are candidates for dose escalation or combined modality studies.