National practice patterns for lymph node irradiation in 197,000 men receiving external beam radiotherapy for localized prostate cancer

Abstract

Purpose-Controversy surrounds the benefit of pelvic lymph node irradiation (PLN-RT) in localized prostate cancer (PCa). Our objective was to determine the practice patterns and predictors of PLN-RT in a national cohort. Materials and methods-The National Cancer Data Base (2005-2015) was leveraged to obtain men diagnosed with non-metastatic PCa treated with external beam radiotherapy (EBRT; n= 197,378). Multivariable logistic regressions were used to assess temporal trends and factors associated with PLN-RT. Results-PLN-RT occurred in 37% of patients overall, which increased to 41% by 2015. When stratified by risk-group, there was no significant difference in PLN-RT over time in low, favorable intermediate, unfavorable intermediate, or high-risk PCa. PLN-RT increased for men with very high-risk disease (51% to 60%; odds ratio per year 1.34, 95% CI 1.06-1.70, p=0.013). Increased odds of PLN-RT was associated with higher risk disease, addition of hormone therapy, treatment at community hospitals, and shorter patient travel distance to treatment facilities. Surprisingly, 26% and 34% of low and favorable intermediate risk PCa received PLN-RT, respectively. Predictors of PLN-RT among these patients included treatment at a community practice and use of brachytherapy or hormone therapy.