By Wiley

Credit: Imad Clicks from Pexels

After treatment for metastatic prostate cancer, a drop in prostate-specific antigen (PSA) levels in the blood is an indicator that treatment is working. A recent real-world study indicates that reaching a PSA level below 0.2 ng/mL is an indicator of improved patient survival. The study is published online inCANCER.

Multiple phase 3 clinical trials have shown that a PSA level below 0.2 ng/mL is the best cutoff for determining a patient's prognosis. Real-world data are lacking, however, and physicians often use other metrics, such as percentage of PSA decline, to assess treatment response. To determine whether there is a PSA response target associated with the most favorable outcome in community-dwelling adults with metastatic prostate cancer, investigators analyzed Veterans Health Administration data on 4,890 patients who received testosterone deprivation therapy with or without other treatments in 2018–2023 for metastatic hormone-sensitive prostate cancer.

Over a median follow-up of approximately 2 years, 896 patients died. Patients whose PSA levels dropped below 0.2 ng/mL within 9 months of starting treatment were 54% less likely to die than patients whose levels did not drop this low, whether their PSA levels also decreased by at least 90% or not. Patients who had at least a 90% PSA decline but did not achieve a PSA level of less than 0.2 ng/mL had no improvement in survival. The findings suggest that patients who do not experience a PSA drop below 0.2 ng/mL could be candidates for more aggressive treatments. Also, patients who received testosterone deprivation therapy plus another drug to further block testosterone were more likely to reach a PSA level below 0.2 ng/mL.

"These data show that we need to target a PSA below 0.2 ng/mL as our metric of success to optimize outcomes for our patients with metastatic prostate cancer," said corresponding author Stephen J. Freedland, M.D., professor of urology at Cedars-Sinai and staff physician at the Durham VA Medical Center.