Trends in risk classification at diagnosis and choice of primary therapy for prostate cancer: An analysis of 10 839 patients from the Nara Urological Research and Treatment Group registry between 2004 and 2015

Objective To evaluate trends in risk classification at diagnosis and choice of primary therapy in patients diagnosed with prostate cancer. Methods This retrospective study included 10 839 patients who were newly diagnosed with prostate cancer between 2004 and 2015 at 23 Japanese institutions. Risk classification and primary therapies between 2004 and 2015 were evaluated. The trends in risk classification and primary therapy were evaluated using chi‐squared tests for trend during four periods (2004–2006; 2007–2009; 2010–2012; and 2013–2015). Binary logistic analysis was used to evaluate the extent to which factors such as age, risk classification, and institution influenced primary therapy choice in the 2013–2015 cohort. Results The number of patients with very‐low or low‐risk classification (P