PCA3 predicts prostate tumor volume and could indicate AS suitability
MedWire News: Prostate cancer patients' urinary prostate cancer antigen 3 (PCA3) scores are strongly indicative of tumor volume, and could be a useful marker of suitability for treatment with active surveillance (AS), study findings show.
The optimal selection of prostate cancer patients for AS is currently debated, remark the researchers, who found that a PCA3 score (calculated using the concentrations of PCA3 in messenger RNA and prostate-specific antigen) above 25 accurately predicted prostate tumor volumes of 0.5 cm3 or more.
"Although the PCA3 score has become an increasing diagnostic tool for the selection of biopsy candidates, this predictive value has not been thoroughly assessed among prostate cancer patients eligible for AS or for the characterization of low-volume prostate cancer," say Guillaume Ploussard (CHU Henri Mondor, Créteil, France) and colleagues.
To address this, the team evaluated associations between pre-surgery PCA3 scores in 109 low-risk (prostate-specific antigen [PSA] level ≤10 ng/ml, clinical stage T1c-T2a, biopsy Gleason score ≤6) prostatectomy patients and four post-surgery pathologic findings. These included pT3-4 disease, overall unfavorable disease (OUD; T3-4 and/or primary Gleason pattern 4), tumor volume of at least 0.5 cm3, and insignificant cancer (organ confined, no Gleason pattern 4 or 5, tumor volume below 0.5 cm3).
Mean PCA3 scores were higher in patients with OUD (62.5 vs 51.5 for favorable disease), Gleason score 7-10 cancer (66.7 vs 45.4 for Gleason ≤6), a primary tumor Gleason pattern of 4 (79.1 vs 51.1 for Gleason pattern ≤3), and a tumor volume of at least 0.5 cm3 (58.7 vs 38.3 for <0.5cm3).
Multivariate analysis, accounting for AS criteria such as imaging findings and PSA density, calculated that a high PCA3 (>25) predicted significant prostate cancer with an odds ratio (OR) of 12.7. It also showed that men with high PCA3 scores were 5.4 times more likely to have a tumor volume of at least 0.5 cm3.
In repeated analysis, adjusted for biopsy-specific findings such as the number of positive cores and percent positive cores, men with a PCA3 score of 25 or higher were three fold more likely to have a tumor volume of at least 0.5 cm3 compared with men with a PCA3 score below 25.
While the researchers believe their findings support the hypothesis that PCA3 may improve criteria for AS selection, "we were unable to identify a threshold value for PCA3 that could accurately classify high-risk men with non-organ-confined disease," they conclude in the journal European Urology.
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010
By Sarah Guy