OBJECTIVETo evaluate the outcomes of T3a prostate cancer treated by permanent interstitial brachytherapy combined with external radiotherapy and hormone therapy, and analyse the influence of preoperative factors on prognosis.

METHODSFrom January 2003 to December 2008, 38 pactients with T3a prostate cancer aged from 48 to 81 years (mean: 71 years) were enrolled, with serum prostate specific antigen (PSA) levels ranged from 10.000 to 99.800 µg/L (mean: 56.300 µg/L), Gleason score from 5 to 9 (mean: 7.6) and percentage of positive biopsy cores from 10.0% to 100% (mean: 65.3%). All patients were treated by permanent interstitial brachytherapy combined with external radiotherapy and hormone therapy. Survival curves were calculated using the Kaplan-Meier method. The predictive factors including patient's age, prostate volume, serum pre-treatment PSA, Gleason score and percentage of positive biopsy cores were used for univariate analysis on biochemical failure-free, distant metastasis-free and overall survival.

RESULTSThe mean follow-up was 69 months (range: 9-109 months).Nineteen patients experienced biochemical failure. The average biochemical failure time was 13.4 months (range: 1-40 months). There were 13 patients developed as distant metastatic prostate cancer since average 19.7 months (range: 1-70 months) after brachytherapy. Of all patients, 9 died of prostate cancer recurrence, while 6 passed away because of other reasons, with an average of 52.2 months (range: 9.0- 98.5 months). The 5-year biochemical failure-free survival (BFFS), distant metastasis free survival (DMFS), cancer specific survival (CSS) and overall survival (OS) rate were 44.1%, 68.6%, 82.4 and 75.8%, respectively. Twenty-nine patients experienced grade 1-2 gastrointestinal toxicity and 18 patients experienced grade 1-2 genitourinary toxicity. In univariate analysis, the percentage of positive biopsy cores was significantly correlated with BFFS (χ(2) = 17.240, P = 0.000), DMFS (χ(2) = 18.641, P = 0.000) and OS (χ(2) = 8.970, P = 0.003); the Gleason score was significantly correlated with DMFS (χ(2) = 12.484, P = 0.000) and OS (χ(2) = 6.575, P = 0.010); and patient's age was significantly correlated with OS (χ(2) = 5.179, P = 0.023).

CONCLUSIONSPermanent interstitial brachytherapy combined with external radiotherapy and hormone therapy is alternative for T3a prostate cancer. The percentage of positive biopsy cores is correlated with BFFS, DMFS and OS.