The importance of protein kinase A in prostate cancer: relationship to patient outcome in Radiation Therapy Oncology Group trial 92-02.

Abstract

PURPOSE:

We previously reported that protein kinase A type I (PKA(RIalpha)) overexpression was predictive of outcome in prostate cancer patients treated with radiotherapy (RT) +/- short-term androgen deprivation (STAD) on Radiation Therapy Oncology Group (RTOG) protocol 86-10. Here, we attempt to verify our prior findings and test the hypothesis that the relationship of the length of AD to patient outcome is affected by PKA(RIalpha) overexpression.

EXPERIMENTAL DESIGN:

There were 313 cases in the RTOG 92-02 study cohort with available tissue and suitable staining by immunohistochemistry. Median follow-up was 10.1 years. The intensity of PKA(RIalpha) staining intensity was quantified manually and by image analysis. Multivariate analyses were done for overall mortality using Cox proportional hazards models and for local failure, biochemical failure, distant metastasis, and cause-specific mortality using Fine and Gray's regression models.

RESULTS:

The expression levels of PKA(RIalpha), determined by manual and image analysis, were strongly correlated (P < 0.0001). In the multivariate analyses, manual-quantified and image analysis-quantified PKA(RIalpha) staining intensities were independent predictors of distant metastasis (P < 0.01), local failure (P < 0.05), and biochemical failure (P <or= 0.01). Furthermore, the benefit of long-term AD over STAD was much less when PKA(RIalpha) expression was high.

CONCLUSIONS:

PKA(RIalpha) overexpression has been shown in two RTOG trials to be associated with an increased risk of failure after AD + RT. In this series of contemporary high-risk patients, PKA(RIalpha) overexpression was associated with diminished response to LTAD + RT relative to STAD + RT, suggesting that such patients would be ideal for a PKA(RIalpha) knockdown strategy.

• Authors: Alan Pollack, Kyounghwa Bae, Li-Yan Khor, Tahseen Al-Saleem, M Elizabeth Hammond, Varagur Venkatesan, Roger W Byhardt, Sucha O Asbell, William U Shipley, Howard M Sandler
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 15 Issue 17 Pg. 5478-84 (Sep 01 2009) ISSN: 1557-3265 [Electronic] United States
• PMID: 19706804 (Publication Type: Clinical Trial, Phase III, Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Androgen Antagonists
• Biomarkers, Tumor
• Cyclic AMP-Dependent Protein Kinase Type I

Topics

• Adult
• Aged
• Aged, 80 and over
• Androgen Antagonists (therapeutic use)
• Biomarkers, Tumor (biosynthesis)
• Cohort Studies
• Combined Modality Therapy
• Cyclic AMP-Dependent Protein Kinase Type I (biosynthesis)
• Humans
• Male
• Middle Aged
• Multivariate Analysis
• Proportional Hazards Models
• Prostatic Neoplasms (drug therapy, enzymology, radiotherapy)
• Radiotherapy Dosage
• Treatment Outcome