Carcinoma of the tonsillar fossa. Significance of dose of irradiation and volume treated in the control of the primary tumor and metastatic neck nodes

Abstract In patients treated for carcinoma of the tonsillar fossa by irradiation alone or preoperative irradiation and surgery a close correlation was observed between the doses of irradiation and adequacy of the portals, with control of the tumor in the primary and the neck lymph nodes. Radiation alone, at doses in the range of 5500 to 6000 rad will adequately control T 1 lesions; for T 2 tumors, 6000–6500 rad are necessary; and for T 3 − T 4 tumors, 7000–7500 rad. The neck nodes tumor is controlled with doses of 5000 rad when there is only subclinical disease ( N 0 ), 6000 rad for N 1 nodes, 6000–6500 rad for N 2 , and 6500–7500 rad for N 3 nodes, depending on the number of fractions. Approximately 50% ofthe patients failing in stages T 3 and T 4 had inadequate coverage of the entire areas of potential marginal tumor spread by the irradiation portals. In patients who were treated with preoperative irradiation, usually 3000 rad in 3 weeks, a greater proportion of pathological specimens with no evidence of tumor were seen in the patients with T 1 − T 2 or N 0 − N 1 lymph nodes. There were almost no failures in the patients with no pathological evidence of residual tumor, in contrast to over 50% of the patients with persistent tumor showing primary recurrences, and 45% of the patients with persistent tumor in the neck nodes developing neck failures. This suggests that higher doses oC preoperative irradiation, which produce a high number of negative specimens, may result in greater tumor control. This study emphasizes the significance of the dose of radiation delivered and the volume treated in patients with carcinoma of the tonsil managed by irradiation alone or combined with a surgical procedure.