Detectable prostate-specific antigen after radiotherapy for clinically localized prostate cancer

Area of Science:

• Oncology
• Radiation Oncology
• Urology

Background:

• Assessing prostate-specific antigen (PSA) kinetics post-radiotherapy (RT) is crucial for predicting outcomes.
• The role of undetectable PSA after RT ± androgen deprivation therapy (ADT) in prostate cancer mortality (PCSM) requires further investigation.

Purpose of the Study:

• To determine the incidence and timing of undetectable PSA (≤0.1 ng/mL) after RT ± ADT.
• To evaluate the association between detectable PSA levels at 6 and 12 months post-treatment and PCSM.

Main Methods:

• Population-based study of 5299 men undergoing RT in Stockholm County (2006-2020).
• Analysis of PSA levels and timing until death or emigration.
• Competing risk regression used to assess the association between PSA levels and PCSM.

Main Results:

• Most patients receiving RT+ADT achieved undetectable PSA (≤0.1 ng/mL) by 6 and 12 months.
• In the RT+ADT group, detectable PSA at 6 and 12 months was significantly associated with higher PCSM (sHRs 6.91 and 37.9, respectively).
• 12-year PCSM rates were substantially lower for patients with undetectable PSA at 6 and 12 months post-RT+ADT compared to those with detectable PSA.

Conclusions:

• Achieving an undetectable PSA level post-RT+ADT is associated with reduced prostate cancer mortality.
• Elevated PSA levels at 6 and 12 months after RT+ADT predict increased PCSM.
• Timely restaging and intensified salvage treatment are recommended for patients with persistently detectable PSA.