Variation in national use of long-term ADT by disease aggressiveness among men with unfavorable-risk prostate cancer.

Abstract

54 Background: Current National Comprehensive Cancer Network (NCCN) guidelines uniformly recommend long-term androgen deprivation therapy (ADT) for all men with high-risk prostate cancer. We sought to determine whether the use of long-term ADT varied by the subcategory of disease, including the recently-defined subcategories of high-risk disease (favorable, other, and very-high) versus intermediate-risk disease. Methods: We identified 5,836 patients with NCCN intermediate-, high-, or very high-risk prostate cancer diagnosed between 2004 and 2007 and managed with external beam radiation therapy (EBRT) using the Surveillance, Epidemiology, and End Results database linked to Medicare claims data. Patients were stratified by risk group: intermediate-risk, favorable high-risk (previously defined and validated as T1c, Gleason 4+4=8, PSA < 10 ng/mL or T1c, Gleason 6, PSA > 20 ng/mL), other high-risk, or very high-risk. We used competing risks regression to estimate the rates of long-term (≥ 2 years) ADT in each of these groups. Differences were compared using multivariable regression modeling, adjusting for year of diagnosis, race, marital status, income level, age, and comorbidity. Results: Men with favorable high-risk prostate cancer were significantly less likely to receive 2 years of ADT than others with high-risk disease (21.9% vs. 29.3%, adjusted hazard ratio [AHR] 0.78, 95% confidence interval [CI] 0.67-0.90, p = 0.001), and similarly likely as those with intermediate-risk disease (AHR 1.08, 95% CI 0.94-1.25, p = 0.288). Others with high-risk disease were less likely to receive 2 years of ADT than those with very high-risk cancer (29.3% vs 36.4%, AHR 0.84, 95% CI 0.74-0.96, p = 0.010). Conclusions: Patients with EBRT-managed high-risk prostate cancer received significantly different rates of long-course ADT based on subclassification. Despite NCCN guidelines recommending long-term ADT for all high-risk or very high-risk prostate cancer, our results might reflect the view that these patients represent a heterogeneous group, with favorable high-risk cancer possibly warranting less aggressive therapy than other high-risk or very high-risk disease.