ABSTRACT
INTRODUCTION: Prostate cancer (PCa) is the second most prevalent neoplasm among men in the world. Its treatment has a wide spectrum of alternatives and variables, ranging from active surveillance through radio and/or brachytherapy, to surgery. OBJECTIVE: The present work aimed to identify the predictive factors for biochemical recurrence and to evaluate the toxicity of the treatment using the association of external beam radiation therapy (EBRT) with high dose rate brachytherapy (HDR-BT) applied in the treatment of patients with prostate cancer. METHODS: Longitudinal retrospective study, using a prospectively collected database between 2005 and 2014 of 186 consecutive patients records with a diagnosis of low, intermediate, or high-risk prostate cancer treated with EBRT combined with HDR-BT, in a single medical institution located in the city of Campinas, SP, Brazil (Radium Institute). PSA increase over 2 ng/ml above the nadir PSA was considered as biochemical recurrence, following the definition of the Phoenix Consensus. Continuous and clinically relevant categorical variables (age, initial PSA, delivered dose in EBRT, number of implants, number of positive cores in transrectal biopsy, use of hormone blockade, Gleason score, TNM staging, post treatment PSA and PSA Nadir) were evaluated with absolute (n) and percentage (%) values using multiple logistic regression and validated our previously described optimal PSA nadir as predictor of biochemical recurrence. RESULTS: Post treatment PSA was the only independent predictor of biochemical recurrence, P<0.0001. The lower the PSA nadir the lower the biochemical recurrence risk (P=0.0009). PSA nadir >1 was the best cutoff (P=0.018) determinant of biochemical recurrence. The incidence of grade 3 late toxicity to the genitourinary tract was 0.6%, and there were no cases of severe complications to the gastrointestinal tract. CONCLUSION: External Beam Radiation Therapy conjugated to Brachytherapy in the treatment of Prostate Cancer has demonstrated low biochemical recurrence rates, mainly when PSA nadir <1, with low toxicity into both GU and GI tracts.