KLK3 and prostate cancer: Nevertheless, some researchers have found that the association between PSA level and prognosis may not be linear; patients with low PSA concentrations (PSA ≤ 4 ng/mL) have been reported to have more aggressive prostate cancer, a worse prognosis than patients with intermediate PSA concentrations (PSA 4–10 ng/mL), and to be prone to achieve unsatisfactory results with conventional local treatment (LT), including radical prostatectomy (RP) and radiotherapy (RT) (Gosselaar, Roobol & Schröder, 2005; Schröder et al., 2000; Wilt, 2014).