[Clinical study of proton radiotherapy in urological cancers]

Therapy with proton beam is superior to that with photon beam in concentrating the dose within a lesion. Fifteen patients with urinary malignant tumors were treated by proton irradiation during the period from June, 1985 to March, 1989 at Particle Radiation Medical Center, University of Tsukuba. Four patients were with renal cell carcinoma, five with prostatic cancer and six with bladder cancer. Treatment results were assessed by change in tumor size either three or six months after the irradiation. In all the four cases with renal cell carcinoma, the tumor sizes were found to be unchanged without any enlargement. Of the five cases with prostatic cancer, two showed that the treatment was effective and the tumor sizes in the other three cases were found to be unchanged. In three of the six cases with bladder cancer the tumors disappeared while the treatment was found effective in two other and it did not cause any enlargement of the tumor in the remaining one. Although local control of the tumor was successful in all the cases, one patient with prostatic cancer and three with bladder cancer died of cancer. Various side effects, such as radiation cystitis, were observed. This prospective therapy is expected to replace the conventional photon therapy. However, some improvement is needed to make full use of the advantageous properties in dose distribution. Combination therapy with other general therapy is required for some cases.