Trends in primary treatment for localized prostate cancer according to the availability of treatment modalities and the impact of introducing robotic surgery

Objectives We aimed to investigate the effect of available treatment modalities on primary treatment selection in patients with localized prostate cancer and that of introducing robotic surgery. Methods We retrospectively studied 12 061 patients diagnosed with localized prostate cancer between 2004 and 2018 from 21 institutions. These institutions were divided into five groups according to the availability of surgery and radiotherapy. Differences in primary treatment selection between the institutions were investigated, and the predictive factors involved in the selection were explored. Results Surgery, radiotherapy, androgen deprivation therapy, and active surveillance/watchful waiting were selected as primary treatment in 4115, 3621, 3188, and 821 patients, respectively, while the remaining 316 patients selected other modalities. The number of patients, particularly young patients, was much higher in institutions with both surgery and radiotherapy. With the introduction of robotic surgery, open radical prostatectomy has decreased, and robotic surgery made up approximately 70% of all prostatectomies. Institutions with both surgery and radiotherapy tended to treat patients with very low or low risk by surgery or radiotherapy, while institutions without surgery and radiotherapy tended to select active surveillance or watchful waiting. Multivariate analysis revealed that primary treatment selection for prostate cancer was affected not only by clinical factors, but also by the available modalities in each institution. Conclusions Differences in available treatment modalities affect the selection of primary treatment for localized prostate cancer. Introduction of robotic surgery also has a strong influence on the number of patients in each institution.