Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, MI.
To investigate the prognostic utility of the percentage of cancer volume (PCV) in needle biopsy specimens for prostate cancer patients treated with dose-escalated external beam radiotherapy.
The outcomes were analyzed for 599 men treated for localized prostate cancer with external beam radiotherapy to a minimal planning target volume dose of 75 Gy (range, 75-79.2). We assessed the effect of PCV and the pretreatment and treatment-related factors on the freedom from biochemical failure, freedom from metastasis, cause-specific survival, and overall survival.
The median number of biopsy cores was 7 (interquartile range, 6-12), median PCV was 10% (interquartile range, 2.5-25%), and median follow-up was 62 months. The PCV correlated with the National Comprehensive Cancer Network risk group and individual risk features, including T stage, prostate-specific antigen level, Gleason score, and percentage of positive biopsy cores. On log-rank analysis, the PCV stratified by quartile was prognostic for all endpoints, including overall survival. In addition, the PCV was a stronger prognostic factor than the percentage of positive biopsy cores when the two metrics were analyzed together. On multivariate analysis, the PCV predicted a worse outcome for all endpoints, including freedom from biochemical failure, (hazard ratio, 1.9; p = .0035), freedom from metastasis (hazard ratio, 1.7, p = .09), cause-specific survival (hazard ratio, 3.9, p = .014), and overall survival (hazard ratio, 1.8, p = .02).
For patients treated with dose-escalated external beam radiotherapy, the volume of cancer in the biopsy specimen adds prognostic value for clinically relevant endpoints, particularly in intermediate- and high-risk patients. Although the PCV determination is more arduous than the percentage of positive biopsy cores, it provides superior risk stratification.
Written by:
Vance SM, Stenmark MH, Blas K, Halverson S, Hamstra DA, Feng FY. Are you the author?
Reference: Int J Radiat Oncol Biol Phys. 2011 Nov 4. Epub ahead of print.
doi: 10.1016/j.ijrobp.2011.09.005
PubMed Abstract
PMID: 22056069
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