• Gregory S Merrick, Wayne M Butler, Kent E Wallner, Robert W Galbreath, Jonathan H Lief, and Edward Adamovich.
• Schiffler Cancer Center, Wheeling Hospital, Wheeling, West Virginia 26003-6300, USA. SchifflerCancerCenter@wheelinghospital.com
• Cancer J. 2004 Jan 1; 10 (1): 54-60.

PurposeThe purpose of this paper was to evaluate the relationship between the percentage of positive biopsies and the biochemical outcome in hormone-naive patients undergoing permanent prostate brachytherapy with or without supplemental external-beam radiation therapy.Materials And MethodsFour hundred thirteen hormone-naive patients underwent prostate brachytherapy for clinical T1c-T2b NxM0 (1997 American Joint Committee on Cancer classification) adenocarcinoma of the prostate gland from April 1995 through June 2001. The median patient age was 66.9 years, and the median pretreatment prostate-specific antigen value was 6.8 ng/mL. The median follow-up was 52 months. Patients were stratified by percentage of positive biopsy results into the following cohorts: < 34%, 34%-50%, and > 50%. The influences of percentage of positive biopsy results, patient age, clinical T stage, Gleason score, pretreatment prostate-specific antigen value, risk group, prostate volume, supplemental external-beam radiation therapy, isotope, percentage of prescribed dose covering 90% of the target volume (D90), and volume receiving 100%, 150%, and 200% of the prescribed dose (V100/150/200) were evaluated. Biochemical disease-free survival was defined by the American Society of Therapeutic Radiology and Oncology consensus definition.ResultsFor all 413 patients, the 7-year actuarial freedom from biochemical progression rate was 99.4%, 94.3%, and 89.2% when stratified by percentage of positive biopsy results in the < 34%, 34%-50%, and > 50% groups, respectively. When low-, intermediate-, and high-risk patients were stratified by percentage of positive biopsy results, a nonsignificant trend for increased biochemical progression was noted with increasing positive biopsy results. In multivariate analysis, percentage of positive biopsy results and pretreatment prostate-specific antigen value were the only significant predictors of biochemical outcome. The median postimplantation prostate-specific antigen value for all biochemically disease-free patients was < 0.1 ng/mL, regardless of risk group or percentage of positive biopsy results cohort.DiscussionMultivariate analysis demonstrated that percentage of positive biopsy results and pretreatment prostate-specific antigen value were statistically significant predictors of 7-year biochemical progression-free survival. However, the relatively small absolute differences in biochemical outcome based on percentage of positive biopsy results may be a result of radiation dose escalation with the utilization of generous periprostatic treatment margins.

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