(HealthDay News) — Prostate-specific antigen (PSA) levels 3 months after radiotherapy (RT) are strong markers of prostate cancer outcomes for patients with intermediate- and high-risk disease, according to a study published online in Cancer.
Alex K. Bryant, from University of California at San Diego, and colleagues used Veterans Affairs data to identify 5783 patients with intermediate-risk or high-risk localized prostate cancer who were diagnosed between 2000 and 2015 and treated with RT and androgen deprivation therapy. Patients were characterized by 3-month post-RT PSA values: <0.10 ng/mL, 0.10 to 0.49 ng/mL, and ≥0.50 ng/mL.
The researchers found that a higher 3-month PSA level was strongly associated with biochemical progression-free survival (bPFS), prostate cancer-specific survival (PCSS), and overall survival (OS). Greater hazards were noted for patients with a 3-month PSA level ≥0.50 ng/mL versus a 3-month PSA value <0.10 ng/mL (hazard ratios: bPFS, 5.23; PCSS, 3.97; and OS, 1.50 [P<0.001 for all]). Greater hazards were also seen for patients with a 3-month PSA value of 0.10 to 0.49 ng/mL (hazard ratios: bPFS, 2.41 [P<0.001]; PCSS, 2.29 [P<0.001]; and OS, 1.21 [P=0.003]). When analyzed separately, 3-month PSA levels were found to be predictive of OS in the high-risk group (P<0.001) but not the intermediate-risk group (P=0.21).
“The 3-month PSA measurement may augment clinical decision making and holds promise as a potential surrogate end point in clinical trials,” the authors write.
Bryant AK, D’Amico AV, Nguyen PL, et al.Three‐month posttreatment prostate‐specific antigen level as a biomarker of treatment response in patients with intermediate‐risk or high‐risk prostate cancer treated with androgen deprivation therapy and radiotherapy. Canc. DOI:10.1002/cncr.31400. [Published online May 4, 2018]