Clinical evaluation of high-dose-rate brachytherapy (HDR) for patients with tongue cancer: Comparison with low-dose-rate brachytherapy (LDR)

For the past several decades, low-dose-rate (LDR) interstitial brachytherapy has been an accepted method of treatment for patients with early tongue cancer, in consideration of a high local control rate and preservation of shape and function of the tongue. However, LDR caused some problems, e.g. radiation exposure to medical staff, and the necessity of isolating patients. Recently, high-dose-rate (HDR) brachytherapy, which is free from these problems, has been developed and applied to various malignant tumors. The aim of this study was to evaluate the usefulness of HDR for stage I-II tongue cancer. Twenty-five patients with stage I-II tongue cancer underwent HDR between 1995 and 1999. The status of local control and late neck metastasis, the survival rate, and the frequency of bone necrosis of these patients were examined in comparison with a historical control, composed of 71 patients who underwent LDR between 1980 and 1995. The following results were obtained. 1) The local control rate in the HDR group was 75% in stage I and 54% in stage II patients, while that in the LDR group was 91% in stage I and 84% in stage II. 2) There were no apparent differences in the frequency of late neck metastasis between the two groups. 3) The survival rate in the HDR group was 64% in stage I and 38% in stage II patients, while that in the LDR group was 85% in stage I and 71% in stage II. 4) Osteonecrosis occurred earlier and more frequently in the HDR group. 5) These results showed that great caution is necessary in performing HDR therapy, until further studies are done using many institutions.