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By Liam Davenport
06 May 2009
Urology 2009; 73: 1087–1091
MedWire News: Among patients with
low-risk prostate cancer, the risk for Gleason sum upgrading (GSU)
is significantly increased in those with fewer cores taken at
prostate biopsy, say researchers.
Previous estimates have indicated that
approximately 29% of patients undergo GSU between initial assessment
and the analysis of radical prostatectomy specimens. However, these
models have not taken into account the effect of the number of
biopsy cores.
To investigate further, Pierre Karakiewicz,
from the University of Montreal Health Center in Quebec, Canada, and
colleagues examined data on 301 low-risk prostate cancer patients
who underwent an extended prostate biopsy involving ≥10 cores.
Low-risk prostate cancer was defined as
clinical stage T1c–T2a disease, prostate-specific antigen (PSA) ≤10
ng/ml, and biopsy Gleason sum <6, while GSU was defined as upgrading
from biopsy Gleason sum 5–6 to radical prostatectomy Gleason sum ≥7.
The average age of the patients was 65.8 years,
the average PSA level was 5.7 ng/ml, the average prostate volume was
56.0 cm³, 74.8% of patients had clinical stage T1c
disease, and 81.7% had biopsy Gleason sum 6. The median number of
biopsy cores taken was 18, and the median interval between biopsy
and radical prostatectomy was 14 weeks.
Grade agreement between biopsy and radical
prostatectomy was found in 47.5% of patients, while 38.5%
experienced upgrading, with 31.9% experiencing a clinically
significant GSU to Gleason sum >7. The rate of upgrading was
significantly greater in men who had 10–12 cores taken compared with
those who had 13–18 or >18 cores taken, at 47.9% versus 31.6% and
23.5%, respectively.
Multivariate analysis indicated that, in a
model including PSA level, clinical stage, year of diagnosis, and
biopsy Gleason sum, only biopsy Gleason sum was an independent
predictor of upgrading, and the combined accuracy of the model was
57.1%.
Adding prostate volume, number of biopsy cores
taken, and the number of positive cores into the model increased the
combined accuracy of the model for predicting upgrading by 9.0% to
66.1%. Independent predictors were biopsy Gleason sum, prostate
volume, number of cores taken, and number of positive cores.
The team writes in the journal Urology:
“The number of biopsy cores taken represents one of the foremost
predictors of clinically significant GSU and should be taken into
consideration during decision-making for patients with localized
prostate cancer.
“Our model provides a decision framework that
considers the effect of the number of cores on the risk of GSU and
allows the integration of this information in clinical
decision-making.”
MedWire (www.medwire-news.md)
is an independent clinical news service provided by Current Medicine
Group, a part of Springer Science+Business Media. © Current Medicine
Group Ltd; 2009
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