EARLY-STAGE NASOPHARYNGEAL CARCINOMA - RADIOTHERAPY DOSE AND TIME FACTORS IN TUMOR-CONTROL

Objective: To evaluate radiotherapy dose and length of treatment in th e control of early stage nasopharyngeal carcinoma (NPC) treated with a combination of external radiotherapy and brachytherapy. Materials & M ethods: We reviewed the records of 133 patients with early stage nasop haryngeal carcinoma (stage I or II, AJC/UICC staging system) who recei ved definitive radiotherapy in Chang Gung Memorial Hospital from 1979 to 1991. The median follow-up time was 7.1 years with a minimum of 2 y ears. All patients were treated with megavoltage external radiotherapy to the nasopharynx area (63-72 Gy) followed by high dose rate intraca vitary brachytherapy (5-16.5 Gy in one to three fractions, spaced 1-2 weeks apart). The median total dose and time of irradiation was 75 Gy (69.8-81.4 Gy) and 11.6 weeks (7.8-20 weeks) respectively. Survival an alysis was used to examine the effect of several variables on prognosi s. Results: The 5-year rates were 86.4% for local control, 84.7% for d isease free survival, 88.5% for actuarial survival and 84.2% for overa ll survival, The treatment group (combination of time and dose of irra diation) was the most important prognostic factor according to Cox's p roportional hazard model. Patients receiving radiation at a total dose of less than or equal to 75 Gy completed in <12 weeks showed the best prognosis. Conclusion: Treatment time and total treatment dose are bo th important factors in treating early stage NPC, Decreasing the total radiation time to <12 weeks and not exceeding a radiation dose of 75 Gy gave the best results.