After treatment for metastatic prostate cancer, a drop in prostate-specific antigen (PSA) levels in the blood is an indicator that the 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 by Wiley online in CANCER, a peer-reviewed journal of the American Cancer Society.

Multiple phase 3 clinical trials have shown that a PSA level below 0.2 ng/mL is the best cut-off 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 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 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, MD, professor of Urology at Cedars-Sinai and Staff Physician at the Durham VA Medical Center.

Source: Wiley