Treatment of prostatic cancer using daily intermittent multiportal therapy (DIMT) technique

In the treatment of prostatic cancer using a newly proposed intermittent multiportal therapy (DIMT), acute reactions, change in tumor marker levels, and complications more than 6 months after treatment were evaluated. From June 1989 to September 1990, 26 patients with prostatic cancer (stage A2, 3 patients; B, 9; C, 2; D, 10; recurrence, 2) were treated. Fifteen patients were followed up for more than one year, with a mean period of 11.6 months. The treatment schedule is 52.5 Gy in 16 fractions in 4 weeks for radical treatment, and 30.0 Gy in 8 fractions in 2 weeks for palliative treatment. The 360 degree rotation about the patient was divided into 16 fractions, and 2 opposing fractions were used in one day as parallel opposed portals to treat the target volume. The fractions were serially treated one per day, so that 8 treatment days produced a total dose of distribution similar to that for conventional conformational therapy. The size of the irradiation field varied from 6 x 6 cm to 9 x 9 cm. No hormonal therapy was performed for stage A2 or B. Acute effect was minimal including skin erythema 2/26 (7%), pollakisuria 1/26 (4%), mild symptoms due to acute proctitis 9/26 (35%). Abnormality high PSA and/or PAP levels returned to the normal range after the treatment in 7 of 10 patients. Local recurrence was detected in 1 patient with stage D, 15 months after completion of therapy, but 21 other patients continued for more than 6 months with no clinical evidence of local recurrence. No residual disease was detected by biopsy undertaken in 10 patients after more than 6 months. No severe complication was detected after more than 6 months except in 1 patient who needed colostomy for the relief of rectal bleeding. DIMT can have the total dose distribution similar to that of conventional conformational therapy without specific devices. Initial results on prostatic cancer treatment were encouraging. (J.P.N.)