Salvage split course brachytherapy for tonsil and soft palate carcinoma: treatment techniques and results

From December 1981 to October 1990, 28 patients with prior irradiation of the oropharynx underwent salvage brachytherapy for a squamous cell carcinoma of the tonsil and/or the soft palate. The patients were free of cervical nodes and without metastatic disease. There were 4 immediate failures of radiotherapy, 14 local recurrences, and 10 new malignancies. The mean size of the lesion was 2.7 +/- 1.7 cm (range, 0.5 to 7 cm). The initial irradiation had delivered 40 to 80 Gy (mean, 69 Gy) to the oropharynx with a mean interval between external therapy and salvage treatment of 22 +/- 28 months. Salvage brachytherapy consisted of two split course implants done 1 month apart, delivering 35 and 30 Gy, respectively. Fifteen patients (46.5%) were clinically disease-free before the second implant and 23 (82%) were clinically disease-free at the end of treatment. Five local failures have been observed without any influence of the tumor size, the topographic site of the tumor, or the histological differentiation. Of the 4 patients who previously had failed with external beam therapy, 3 were disease-free after salvage brachytherapy. Among the 23 patients in complete remission, 4 (17%) presented a local recurrence within a mean time of 5 months. The overall local control rate was 68% with a mean follow-up of 41 +/- 29 months. The overall actuarial survival was 25% and 19% at 2 and 5 years, respectively; it was 30% at 5 years for the patients presenting with lesions less than or equal to 3 cm. Tolerance was acceptable. Among the 23 patients who achieved complete remission, subsequent soft-tissue necrosis was observed in 4 cases. For these 4 patients, the interval between previous radiation therapy and salvage treatment was short (mean, 7 months). Interstitial split course brachytherapy offers an effective and reasonable option for salvage therapy in patients with recurrent and second cancers occurring in the tonsillar region and in the soft palate, even when the tumor arises in a zone that has previously received high-dose irradiation.