External irradiation followed by interstitial brachytherapy in carcinoma of the tongue

Between 1974 and 1978, 22 patients underwent external and interstitial radiation therapy as the primary treatment of carcinoma of the tongue at Jikei University School of Medicine. Primary lesions and regional lymph node metastasis were retrospectively staged according to TNM staging; they were T1N0: 5, T2N0: 6, T3T0: 4, T4N0: 1, T1N1: 1, T2N1: 3, T2N2: 1, T3N2: 1. Primary lesions were usually treated by external irradiation (20 -- 30 Gy) followed by interstitial implantation (50 -- 60 Gy). For external irradiation, a Cobalto 60 and a 4 Mev linear accelerator were used. Between the two treatments, there was a 1 -- 2 week interval. Dosage calculation for interstitial radium implants was based on Paterson-Parker and Quimby tables. Local control was achieved as follows, T1: 6/6 (100%), T2: 8/10 (80%), T3: 0/5 (0%), T4: 0/1 (0%). There was no clear relationship between the combined total dose and the local control rate. For T1 and T2, we obtained a good local control rate even when the interstitial implant was reduced to 45 Gy. Our results suggest that it is possible to substitute the external for a portion of the interstitial dose. We encontered no necrosis. Two patients graded as T2 experienced local recurrence, both of these were at the margin of the primary tumor and ascribable to inappropriate Cesium insertion. After external irradiation, implantation should be to the original, not the decreased tumor. The cumulative survival rates were as follows, 1y: 19/22 (86%), 2y: 8/15 (46%), 3y: 6/6 (46%), 4y: 3/3 (46%), 5y: 1/1 (46%). (author)