[Radiotherapy of the tonsillar region. Analysis of prognostic factors]

We report our personal experience with the treatment of tonsillar cancers at the Otorhinolaryngology-Radiotherapy Department of Umberto I Hospital, Mestre, Italy. The results were analyzed by tumor site and stage, lymph node involvement, treatment type and patient age.

January, 1987, through December, 1995, we treated a hundred and 25 patients with carcinoma of the tonsil and tonsillar region. Most patients were men (M:F = 4:1), with a mean age of 61.9 years (range: 38-87). The lesions were staged at physical examination, chest radiography, bone scintigraphy. US of the liver and neck, CT and/or MRI of the tonsillar region and neck. Eleven patients were in stage I (8.8%), 26 in stage II (20.8%), 31 in stage III (24.8%) and 57 in stage IV (45.6%). Forty-one patients were submitted to tonsillectomy and more/less massive neck dissection: surgery was not radical-in 14 of them. All patients received gamma-photon radiotherapy with a cobalt unit: the minimum dose was 50 Gy after radical surgery and 60 Gy for exclusive irradiation and after nonradical surgery. The hemiblock field technique was always used with the conventional fractionation (2 Gy/day. 1 fraction/day, 5 fractions/week); the treatment was planned with the Theraplan V05-B method on CT scans. When the tolerance dose was reached, the spinal cord was shielded and the dose compensated with 9 MeV electrons. The treatment was discontinued only when needed, and never for more than 7-10 days.

The overall 5-year survival and the 5-year disease-free survival rates were 28% and 45%, respectively; the overall 5-year cause-specific survival rate was 39%. Disease-free survival was 81% in stage I, 52.7% in stage II, 44.2% in stage III and 35.8% in stage IV (p = .005). The 5-year disease-free survival for the patients receiving surgery and irradiation was 62.1%, versus 38.3% for irradiation alone; the rate was 37.6% when neck nodes were involved (N+). One hundred and two patients achieved complete remission (CR), while the other 23 had partial remission (PR). Twenty-eight CR patients recurred; the most common cause of death was failure in primary tumor local control. There were no complications during or after treatment. Secondary lesions were found in 13 patients (10.1%).

Irradiation alone yields fairly good results in early tonsil carcinoma, while the surgery-irradiation combination should be preferred in large tumors. Better results are expected from kinetic and conformal irradiation techniques with 3D calculations on CT and MR images, which should permit to deliver high doses to strictly targeted areas and to reduce side-effects. Other improvements are expected from new combination therapies.