NEW YORK (Reuters Health) - When prostate-specific antigen (PSA) level rises after radical prostatectomy (RP), early salvage radiation therapy (eSRT) is an option. But a large retrospective study highlights the importance of "contextualizing" the absolute value of postoperative PSA according to tumor characteristics, researchers say.
"The hypothesis of the current study was that the impact of PSA level on cancer control after eSRT varies according to tumor characteristics at final pathology. Our results confirmed our hypothesis because PSA level conferred a different BCR (biochemical recurrence) risk after SRT based on pathologic features," they reported online 21 in European Urology.
Dr. Nicola Fossati, of IRCCS Ospedale San Raffaele in Milan, Italy, and colleagues studied 716 node-negative patients with undetectable PSA after surgery who had a rise in PSA after RP. They defined BCR after eSRT as two back-to-back PSA values of 0.2 ng/ml or higher. The median PSA level at eSRT was 0.2 ng/mL (range 0.1-0.3 ng/ml).
"In this retrospective study, we found that cancer control after eSRT greatly depended on pretreatment PSA, and the absolute PSA level had a different prognostic value depending on the pathologic characteristics of the tumor," the researchers report.
In the adjusted analysis, the pre-eSRT PSA level was significantly associated with BCR after eSRT (hazard ratio, 4.89). The study also identified three pathologic risk factors significantly tied to BCR after eSRT: pathologic stage pT3b or higher (HR, 2.07), pathologic Gleason score of 8 or higher (HR, 2.69) and negative surgical margins (HR, 2.50).
According to the researchers, men with at least two of these pathologic features had an increased risk of BCR at five years of 10% per 0.1 ng/ml of PSA level. "In this setting, our results highlighted the need for eSRT administration at the very first sign of PSA increase to maximize cancer control," they write.
On the contrary, the five-year BCR risk increased by only 1.5% per 0.1 ng/ml of PSA in men with one or no pathologic risk factors. "In this patient category, a wait-and-see approach appears to be a reasonable option to avoid overtreatment," the researchers say.
"In this study, for the first time, we showed the importance of contextualizing the absolute value of postoperative PSA according to tumor characteristics," Dr. Fossati and colleagues conclude.
"In other words, the administration of SRT appears to be a decision step similar to whether or not to perform a prostate biopsy for an elevated PSA value at the time of diagnosis. If our findings are confirmed by future studies, urologists and radiation oncologists should integrate the PSA value after surgery with further information (ie, pathologic characteristics). In the future, the use of ultrasensitive PSA assays for close monitoring will allow for further precision of PSA-based thresholds for eSRT initiation," they write.
The study had no funding and the authors have no relevant disclosures. They did not respond to request for comment by press time.
Eur Uro 2015.