Does pretreatment PSA add to predicting long-term survival from prostate cancer?
Presenter: M. Roach III
Affiliation: Univ of California San Francisco, Univ of Michigan
Numerous prognostic indicators, such as Gleason score and tumor stage are known to be significant in assessing risk of recurrence of or death from prostate cancer. Although prostate specific antigen (PSA) is useful in predicting recurrence, its role as an independent prognostic indicator relative to other staging is less clear, given the relatively short time PSA has been in use compared to the long natural history of this disease. This study was performed to determine whether pre-treatment PSA level helped predict long-term survival.
- Pre-established risk groups from RTOG criteria based on T stage and Gleason score were analyzed for 4 year freedom from biochemical failure (FFBCF) based on PSA stratification.
- 4 RTOG risk groups were examined: 1. T1-2, Gleason Score (GS) 2-6; 2. T3, GS 2-6 or T1-2, GS 7; 3. T1-2, GS 8-10 or T3, GS 7; 4. T3, GS 8-10. 4 year FFBCF was then examined for pre-treatment PSA (pPSA) < 10 versus pPSA > 20.
- Patients from UCSF and U of Michigan treated with radiation therapy alone with pPSAs available were eligible.
- Four FFBCF rates when stratified by RTOG risk group matched the 15-year disease specific survival in the larger RTOG group.
- In risk groups 1,2, and 3, pPSA added prognostic information. The 4-year FFBCF for low and high pPSA were 83% versus 47% in group 1., 76% versus 45% in group 2, and 65% versus 25% in group 3 (p < 0.001). Group 4 was not significant (27% versus 28%).
- The ASTRO consensus definition for FFBCF at 4 years is strongly correlated with the expected 15 year DSS stratified by RTOG risk groups.
- Incorporating pPSA should improve our ability to predict death due to prostate cancer.
- Risk group 4 patients are candidates for systemic therapy regardless of PSA.
- This analysis supports pPSA as an independent prognostic indicator in all but the highest risk disease.
- Many patients with higher risk disease are receiving pre-treatment, concurrent, or post- treatment androgen ablation, or a combination of these. How this therapy will effect disease outcome and the significance of each prognostic variable is uncertain.