KLK3 and prostate cancer: Brachytherapy combined with external irradiation provided a 7-year biochemical recurrence-free survival rate of 57% in patients with locally advanced prostate cancer,[11] and image-guided proton therapy provided a 5-year biochemical recurrence-free survival rate of 76%.[12] The biochemical recurrence-free survival rate was 84.6% in this study, which may be related to the small sample size, and bias in age, PSA level, and other factors.