High-dose-rate brachytherapy with local injection of bleomycin for N0 oral tongue cancer - The possibilities of the control of tumor implant by inserting applicators and the decrease in tumor dose

Twenty eight patients with N0 oral tongue cancer were treated with high-dose-rate (HDR) interstitial brachytherapy combined with local injection of bleomycin between December 1997 and June 2001 at the Department of Radiology, National Kyushu Medical Center Hospital. A median dose of 5 mg of Bleomycin was injected locally and 16-20 Gy were delivered to the surroundings of applicators for the control of the tumor implant for initial two days. Two-year local recurrence-free survival rate was 96 % (T1, 2: 100 % (8/8, 15/ 15), T3: 80 % (4/5)). Two-year secondary neck node metastasis rate was 7.1 % (T1: 12.5 % (1/8), T2: 6.7 % (1/15), T3: 0 % (0/5)). There were no tumor implant in any patients. We tried to decrease the minimal tumor dose step by step. The group with a median minimal tumor dose of 60 Gy, 50 Gy, and 40 Gy had a local recurrence rate of 12.5 % (1/8), 0 % (0/14), 0 % (0/6), respectively. Local recurrent rates were not increase by decreasing a minimal tumor dose. Two patients (7%) had secondary neck node metastasis. Late adverse effects were tongue ulcer: 11 % (3/28), oral floor ulcer: 4 % (1/28), and osteonecrosis: 4 % (1/28). These results suggest that control of the tumor implant and the decrease in minimal tumor dose below 60 Gy may be possible with the local injection of bleomycin and delivering doses to the area surroundings the applicators when N0 tongue cancer is treated using ¹⁹²Ir-HDR brachytherapy.