Japanese nationwide multi-institutional cohort study of prostate cancer brachytherapy with permanent seed implantation.

Abstract

e16090 Background: Brachytherapy with permanent iodine-125 seed implantation (PI) has been approved in 2003 in Japan. Multi-institutional cohort study (Japanese Prostate Cancer Outcome Study of Permanent Seed Implantation; J-POPS, NCT00534196) assessing the treatment feature, efficacy, safety and health-related quality of life (QOL) has started in July 2005. Six thousand nine hundred and twenty-seven cases were enrolled to this study until December 2010 from 68 institutes around the country, which is approximately 40% of all the cases treated in Japan at that time. Methods: Patient’s background, cancer character, treatment feature such as combined therapy of external beam or hormone, post PI dosimetric information, treatment efficacy with PSA level, voiding symptoms with IPSS and treatment related adverse events according to NCI-CTCAE are investigated. PSA was measured every 3 months and symptoms accompanied to the treatment were assessed 3 to 6 months after the treatment. Backgrounds and treatment assessments of 2,341 patients enrolled in J-POPS during the initial 2 years are evaluated. Results: Patients’ age ranged from 45 to 89 (median 69) year-old and 99.0% of the cases were performance status 0 (ECOG criteria). Family history of prostate cancer was seen in 6.2%. PSA levels on cancer diagnosis were 1.60 to 42.0 (mean 6.80) ng/ml, clinical stage T2a or less was 89.9%, T2b was 5.2%, T2c was 2.9% and T3a-T3b was 0.8%. Gleason score (GS) less than 7 was 56.6%, GS 7 was 39.7%, and GS above 7 was 3.6%. According to NCCN risk classification, 44.2% was classified as low risk, 48.3% as intermediate risk and 5.7% as high risk. Androgen deprivation therapy (ADT) was performed in 48.5% of the patients and 23.4% was combined with external beam radiation therapy (EBRT). CT scan based first post therapeutic month dosimetry revealed that prostatic mean V100 and D90 for the cases treated with seed alone were 94.8% and 160.7 Gy, respectively. As for adequate control of radiation dose at rectum (mean R100 = 0.3 cc) and urethra (mean D5 = 223.4 Gy), high grade toxicities appeared very seldom. Conclusions: Outcomes of J-POPS will produce clinical evidence of PI that can be internationally accepted.