HIGH-DOSE-RATE VERSUS LOW-DOSE RATE INTERSTITIAL RADIOTHERAPY FOR CARCINOMA OF THE FLOOR OF MOUTH

Purpose: Patients with cancer of the floor of mouth are treated with r adiation because of functional and cosmetic reasons. We evaluate the t reatment results of high dose rate (HDR) and low dose rate (LDR) inter stitial radiation for cancer of the floor of mouth. Methods and Materi als: From January 1980 through March 1996, 41 patients with cancer of the floor of mouth were treated with LDR interstitial radiation using Au-198 grains, and from April 1992 through March 1996 16 patients with HDR interstitial radiation. There were 26 T1 tumors, 30 T2 tumors, an d 1 T3 tumor. For 21 patients treated with interstitial radiation alon e, a total radiation dose of interstitial therapy was 60 Gy/10 fractio ns/6-7 days in HDR and 85 Gy within 1 week in LDR. For 36 patients tre ated with a combination therapy, a total dose of 30 to 40 Gy of extern al radiation and a total dose of 48 Gy/8 fractions/5-6 days in HDR or 65 Gy within 1 week in LDR were delivered. Results: Two-and 5-year loc al control rates of patients treated with HDR interstitial radiation w ere 94% and 94%, and those with LDR were 75% and 69%, respectively. Lo cal control rate of patients treated with HDR brachytherapy was slight ly higher than that with Au-198 grains (p = 0.113). For late complicat ion, bone exposure or ulcer occurred in 6 of 16 (38%) patients treated with HDR and 13 of 41 (32%) patients treated with LDR. Conclusion: HD R fractionated interstitial brachytherapy can be an alternative to LDR brachytherapy for cancer of the floor of mouth and eliminate radiatio n exposure for the medical staff. (C) 1998 Elsevier Science Inc.