Disproportionate expansion of radical prostatectomy among older men in Japan in the robotic surgery era: a nationwide descriptive time series analysis.

Robot-assisted radical prostatectomy (RARP) has rapidly expanded and become the leading surgical approach for prostate cancer in Japan. However, it remains unclear whether the concurrent increase in radical prostatectomy reflects population aging, increased diagnostic activity, or shifts in treatment selection after diagnosis. We performed a nationwide descriptive time-series analysis using publicly available Japanese administrative claims, cancer registry data, population statistics, and hospital function reports. We identified prostate cancer surgeries, laboratory testing, and prostate biopsies through reimbursement codes and analyzed them as annual claim counts. Surgical procedures were categorized as open, laparoscopic, minimally invasive endoscopic, or RARP. Trends from 2016 to 2024 were evaluated, and age-specific metrics for men aged 75-79, 80-84, and ≥ 85 years were referenced to 2018. Prostate cancer surgeries rose from 21,988 in 2016 to 29,548 in 2024. RARP procedures increased from 13,415 to 27,911, comprising 94.5% of all surgeries in 2024. The share of surgeries in men aged ≥ 75 years grew from 12.3% to 30.5% and among men aged ≥ 80 years, it rose from 0.9% to 4.7%. For men aged 80-84 years, the 2024 surgery index reached 463.0, surpassing the indices for population size, incidence, mortality, prostate-specific antigen testing, and biopsy. Radical prostatectomy increased disproportionately among older men in Japan, particularly those aged 80-84 years, predominantly through the expansion of RARP. These population-level trends highlight the need for individualized patient selection based on frailty, life expectancy, tumor risk, and expected treatment benefit to mitigate potential overtreatment in older men.