Prostate-specific antigen (PSA) levels three 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.

Prostate?specific antigen (PSA) measurement after definitive radiotherapy (RT) and androgen deprivation therapy for localized prostate cancer have been proposed as an early prognostic biomarker.

In the current study, the authors investigated the association between 3?month post?RT PSA level and biochemical progression?free survival (bPFS), prostate cancer?specific survival (PCSS), and overall survival (OS).

Radiation therapy may be curative in some types of cancer if they are localized to one area of the body. It may also be used as part of adjuvant therapy, to prevent tumor recurrence after surgery to remove a primary malignant tumor (for example, early stages of breast cancer).

Radiation therapy is synergistic with chemotherapy and has been used before, during, and after chemotherapy in susceptible cancers. The subspecialty of oncology concerned with radiotherapy is called radiation oncology.

Prostate?specific antigen (PSA) measurement

Alex K. Bryant, from University of California at San Diego, and colleagues used Veterans Affairs data to identify 5,783 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 three-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 three-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 three-month PSA level ≥0.50 ng/mL versus a three-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 three-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, three-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 three-month PSA measurement may augment clinical decision making and holds promise as a potential surrogate endpoint in clinical trials," the authors noted. The 3?month PSA measurement might augment clinical decision making and holds promise as a potential surrogate endpoint in clinical trials.

The 3?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.