Outcomes and predictors of T3a prostate cancer treated by permanent interstitial brachytherapy combined with external radiotherapy and hormone therapy
Objective: To 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.
Methods: From 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.
Results: The 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).
Conclusions: Permanent 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.