Role of Interstitial Brachytherapy in Oral and Oropharyngeal Carcinoma: Reflection of a Series of 1344 Patients Treated at the Time of Initial Presentation

Abstract

Our study focuses on a series of 1344 cases of carcinoma of the oral cavity and oropharynx treated between 1973 and 1992. Brachytherapy was always performed with iridium 192, either alone or in combination with external-beam irradiation or with surgery for the treatment of the primary tumor. For the oral cavity, we studied 565 cases of mobile tongue. The local control and overall survival rates, respectively, at 5 years are as follows: for T1, 92% and 70%; for T2, 62% and 42%; and for T3, 50% and 29%. For the subgroup T1T2N0, there was a better prognosis for treatment by brachytherapy of the primary lesion alone (p < 0.0001). Two hundred seven cases of floor-of-mouth carcinoma have been reported. The T3T4 patients were not considered surgical candidates. The local control and overall survival rates, respectively, at 5 years are as follows: for T1, 97% and 71%; for T2, 72% and 42%; and for T3, 51% and 35%. Ninety-seven patients were treated by postoperative brachytherapy. These were patients for whom the margins after surgery were positive or narrow. A technique termed the modified bridge is described for lesions located in the mandible. Carcinomas of the buccal mucosa are rare in our country; only 42 cases were treated in this comparison of two techniques, and the overall survival rate was 48%. Epidermoid carcinomas of the oropharynx have nearly always been treated by a combination of external-beam irradiation and brachytherapy because of the bilateral node risk. Seventy-two patients with epidermoid cancers of the base of the tongue had an overall survival rate of 44%. The tonsil, soft palate, and pillars benefited from the use of the loop technique of brachytherapy combined with external-beam irradiation. Three hundred sixty-one patients were treated. Among these patients were two groups with different prognoses. Patients with tonsil, soft palate, and posterior pillar carcinomas had a local control rate of 84% and an overall survival rate of 57%. Conversely, the anterior pillar and the pharyngoglossal sulcus have a local control rate of only 65% and an overall survival rate of 38%. Statistical analysis revealed the prognostic factors for local control. The complications were classified into four grades: minor (20%), moderate (9%), major (4%), or inducing death (0.2%). The bone complications of grade 2 or 3 are more frequent for the floor of the mouth than for other locations.