Application of 198Au grains for carcinoma of oral cavity

The purpose of this study is to analyze the results of the treatment using gold grain implants over the past 9 years and to evaluate the usefulness of this treatment method.

From January 1985 through April 1993, a total of 45 patients with squamous cell carcinomas of the oral cavity and the oropharynx were treated with 198Au grain (gold grain) at the Department of Radiology, Osaka University Medical School. The initial activity of the grains supplied weekly by the Japan Radioisotope Association was usually 5 mCi (185 MBq), and single implants were usual. In case of combined external irradiation, telecobalt gamma-rays or 4 MV X-rays were used for treatment before implant.

The local control rate for patients with T1 stages was 80% (20/25) and with T2 stages, 59% (10/17). The local control rate was 71% (10/14) for gold grain alone and 72% (13/18) for external irradiation combined with gold grain implants (combined therapy). In combined therapy, the median of the interval between external irradiation and gold grain implants was 21 days. The treatment interval for patients with recurrent diseases was 22 days, 22, 27, 39 and 46, respectively. The progression rate showed a tendency to increase in the patients with longer interval (more than 21 days), and with partial regression after external irradiation (p = 0.0085).

Our findings show that the time interval between external irradiation and gold grain implantation is an important factor in combined therapy. Therefore, we emphasize that the time interval should be shorter than 3 weeks.