[Carcinoma of the oropharynx extended to the base of the tongue: radiosurgical treatment with intraoperative radiotherapy].

Treatment by surgery and postoperative radiotherapy is classical for patients with locally advanced oropharyngeal carcinoma. The poor prognosis of these tumors is associated with the frequency of locoregional relapses, and the survival of the patients treated is more limited according to the initial degree of tumoral involvement of the base of the tongue, which is a critical zone: at this level, the surgical resection must not be too large for a good preservation of the function of the tongue; high doses of radiotherapy are also required here for a fair local tumor control. Intraoperative Radiotherapy (IORT) may be available for delivery of high boosting doses of radiotherapy locally in this target volume. Between March 1988 and March 1992, 39 patients were treated for T3-T4 locally advanced oropharyngeal carcinoma, with 1/4 to 1/2 of the base of the tongue involved; 30 patients were treated for a first localization. Surgery was done by transmaxillary buccopharyngectomy (followed by vascularized myocutaneous flap) for 31 patients with lateral tumors; for 8 patients with median tumor (valleculae), either a conservative susglottic laryngectomy (5 patients) or a total laryngectomy was indicated. Patients treated for the first time underwent also a bilateral node dissection. IORT delivered 20 Gy in the target volume of the resected base of the tongue (prescribed at 90% isodose depth) by the mean of an electron beam of 6 to 13 MeV, with a collimator of 4 or 5 cm of inner diameter. Postoperative radiotherapy was indicated for all patients treated with a first localization. After a minimal follow-up of 6 months, the global survival of 28 patients treated for their first localization was 49% at more than 3 years; 64% of patients treated were locally free of disease. In the same delay, and according to the quality of the surgical resection, the survival of patients treated was 67% and 58%, respectively, if non pathological level of resection was beyond 2 mm, or unless 2 mm from the tumor limit. No complication directly related to IORT was noted. These therapeutic results demonstrate the validity of IORT as a part of a radiosurgical treatment indicated for patients with locally advanced oropharyngeal carcinomas. A longer follow-up of patients treated with a first oropharyngeal tumor is warranted for confirmation of the gain on survival observed.