Improved local control of nasopharyngeal carcinoma after intracavitary brachytherapy boost.

In 1976 we began using intracavitary cesium boost technique as a portion of comprehensive treatment of primary T2 and T3 nasopharyngeal carcinoma. At first, we offered this procedure sporadically to patients with T1 lesions. For the past 10 years, intracavitary boost has been offered to all patients except those with T4 lesions. The radiation therapy program consists of external beam dose of 60-64 Gy, either once daily (q.d.) or twice daily (b.i.d.) schedule, followed by 10-15 Gy boost to mucosal surface by intracavitary implant, making a total of approximately 75 Gy. This article presents the experience at the Massachusetts General Hospital with 146 patients with T1-3 carcinoma of the nasopharynx irradiated from 1970 through 1988. Seventy-six patients were treated with intracavitary boost and 70 patients were treated up to 65-70 Gy by external beam alone. The overall 5-year actuarial local control rate for the T1 lesions was 93% after radiation therapy and intracavitary boost as compared with 54% without brachytherapy boost (p value = 0.057). For the T1-2 lesions, the corresponding local rates after external radiation therapy and brachytherapy boost and after external beam irradiation without boost were 90 and 59%, respectively, with p = 0.001. For the T3 lesions, the rates were 100 and 64%, respectively, with p = 0.090. The reason for improved local control is unclear and may be due to a somewhat higher mucosal dose to the nasopharynx. Hopefully, the improved beneficial local control effects may be reflected in improved patient survival. However, such data require a controlled randomized clinical trial for confirmation.