Investigators have identified factors that could be useful in managing patients who experience rising PSA levels following stereotactic body radiation therapy (SBRT) for prostate cancer, according to a presentation at the American Urological Association’s 2022 annual meeting.
These factors — the timing at which a PSA rise occurs, PSA nadir value, and time to PSA nadir — could help distinguish PSA bounce from biochemical recurrence (BCR) of disease.
Ashley Monaco, BS, of the New York Institute of Technology College of Osteopathic Medicine in Glen Head, New York, and colleagues studied 170 men who underwent primary SBRT. The men had a median age of 72 years and an average follow-up duration of 75 months. Of these, 28 (16%) experienced PSA bounce and 42 (25%) had BCR.
Compared with patients who did not experience PSA bounce or BCR, those with PSA bounce were younger, had significantly lower PSA doubling time, and took significantly longer to reach PSA nadir. Compared with the BCR group, men with PSA bounce had a lower final PSA nadir (median 0.30 vs 0.90 ng/mL) and took longer to reach final PSA nadir (median 38 vs 12 months). PSA bounce occurred significantly earlier than BCR (16 vs 33 months).
The study excluded patients with less than 18 months of follow-up or who were missing more than 3 PSA measurements following SBRT. The investigators defined PSA bounce as a rise of greater than 0.2 ng/mL over the pre-rise nadir followed by a decline without intervention. They defined BCR according to Phoenix criteria (PSA nadir plus 2 ng/mL).
Monaco A, Sommer J, Mendelson J, et al. Distinguishing between prostate specific antigen bounce and biochemical recurrence following stereotactic body radiotherapy for prostate cancer. Presented at AUA 2022, May 13-16, 2022, New Orleans, Louisiana. Abstract PD22-09.