Tumor control outcomes of patients treated with trimodality therapy for locally advanced prostate cancer

Abstract

Objectives To evaluate, in a pilot study, the tumor control outcomes of our approach and define the pretreatment characteristics that predict a response to therapy. Patients with advanced clinically localized prostate cancer have a high likelihood of prostate-specific antigen (PSA) failure 3 to 5 years after initial treatment. We adopted trimodality therapy (neoadjuvant and adjuvant androgen ablation, external beam radiotherapy [RT], and a brachytherapy boost) to augment biochemical disease-free survival in this patient population. Methods From 1997 to 2000, 93 patients with clinical Stage T2b or greater, or PSA level greater than 10 ng/mL, or Gleason score 7 or greater were treated with external beam RT followed by palladium-103 brachytherapy. Two to three months before external beam RT, an 8 to 9-month regimen of leuprolide and an oral antiandrogen was initiated. Patients were followed up at 3 to 4-month intervals with PSA determination and digital rectal examination. Perineural invasion, the percentage of cancer in biopsy cores, pretreatment PSA level, clinical T stage, and Gleason score were analyzed as prognostic factors for biochemical failure defined by both the American Society for Therapeutic Radiology and Oncology (ASTRO) criteria and PSA level greater than 0.2 ng/mL. Results The median length of follow-up was 45 months. The overall probability of biochemical failure using a PSA level greater than 0.2 ng/mL at 4 years was 79% (95% confidence interval 69% to 89%). With the ASTRO criteria, the overall failure rate at the same point was 77% (95% confidence interval 68% to 87%). Gleason score ( P = 0.07) showed a trend toward predicting biochemical failure using the PSA level greater than 0.2 ng/mL criterion. Conclusions Trimodality RT offers excellent tumor control in patients with poor prognosis who often relapse early. Longer follow-up will be important to determine whether these results are durable over time.