Post-Treatment PSA Level May Predict RT Outcomes

Prostate-specific antigen (PSA) levels three months after radiotherapy (RT) are strong markers of prostate cancer outcomes, according to a new study.

Researchers at the University of California, San Diego (UCSD, USA) and Dana-Farber Cancer Institute (Boston, MA, USA) conducted a study involving 5,783 patients with intermediate-risk or high-risk localized prostate cancer diagnosed in the years 2000-2015 and treated with RT and androgen deprivation therapy. The aim of the study was to examine the association between three-month post-RT PSA level and biochemical progression-free survival (bPFS), prostate cancer-specific survival (PCSS), and overall survival (OS).

In all, there were 2,651 patients with intermediate-risk and 3,132 with high-risk disease, with about 11% harboring a three-month PSA level higher than 0.50 ng/mL, which was found to be strongly associated with each outcome, as compared to patients with a three-month PSA value lower than 0.10 ng/mL. When the groups were analyzed separately, three-month PSA level was found to be predictive of OS in the high-risk group, but not in the intermediate-risk group. The study was published on May 4, 2018, in Cancer.

“The three month post‐RT PSA level appears to be a strong prognostic biomarker for bPFS, PCSS, and OS in patients with intermediate‐risk and high‐risk prostate cancer, particularly those with high‐risk disease,” concluded lead author Alex Bryant, BSc, of the UCSD department of radiation medicine and applied sciences, and colleagues. “The three month PSA measurement may augment clinical decision making and holds promise as a potential surrogate endpoint in clinical trials.”

PSA is a glycoprotein enzyme secreted by the epithelial cells of the prostate gland, and is encoded in humans by the kallikrein-3 (KLK3) gene. PSA is produced for the ejaculate, where it liquefies semen in the seminal coagulum, allowing sperm to swim freely; it is also believed to be involved in dissolving cervical mucus, allowing the entry of sperm into the uterus. PSA is present in small quantities in the serum of men with healthy prostates, but is elevated in the presence of prostate cancer, prostatitis or benign prostatic hyperplasia (BPH).

Related Links:
University of California, San Diego
Dana-Farber Cancer Institute