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Urology. 2014 Aug;84(2):393-9. doi: 10.1016/j.urology.2014.04.016. Epub 2014 Jun 7.

Modeling and analysis of Gleason score 8-10 prostate cancers in the REDUCE study.

Author information

1
Division of Urologic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO. Electronic address: andrioleg@wustl.edu.
2
Bostwick Laboratories, Glen Allen, VA.
3
Department of Urology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA.
4
Department of Urology, Medical University of Vienna, Vienna, Austria.
5
Department of Urology, Scientific Institute Hospital San Raffaele, Milan, Italy.
6
Department of Urology, Tampere University Hospital, University of Tampere, Tampere, Finland.
7
Department of Urology Research, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN.
8
Pharmaceutical Product Development, Wilmington, NC.
9
GlaxoSmithKline, Research Triangle Park, Raleigh-Durham, NC.
10
GlaxoSmithKline R&D, King of Prussia, PA.

Abstract

OBJECTIVE:

To explore explanations for the numerical imbalance of biopsy-detected Gleason 8-10 prostate cancers (PCa) diagnosed in years 3-4 in the dutasteride and placebo groups of the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) study.

METHODS:

REDUCE was a 4-year, randomized, double-blind, placebo-controlled trial of dutasteride (0.5 mg/d) vs placebo for PCa risk reduction. We modeled the incidence of Gleason 8-10 cancer and used logistic regression analysis to evaluate the effects of baseline predictors of PCa, as well as post-baseline prostate volume at the time of biopsy, on PCa diagnosis. We compared needle biopsy Gleason scores with corresponding surgery Gleason scores. All statistical tests conducted were 2-sided.

RESULTS:

Had there been a scheduled biopsy occurring only at year 4, we estimated a similar incidence of Gleason 8-10 PCa in the dutasteride (n = 45) and placebo (n = 46) groups. Two biopsy Gleason 7 cancers in the placebo group (n = 150) were upgraded to Gleason 8-10 cancer on prostatectomy, and no patients in the dutasteride group (n = 111) were upgraded. Logistic regression analysis demonstrated the effect of prostate volume on Gleason 8-10 cancer diagnosis.

CONCLUSION:

Although modeling of REDUCE data showed a similar incidence of Gleason 8-10 cancer in the dutasteride and placebo groups at year 4, an association between dutasteride and Gleason 8-10 cancer cannot be definitely excluded. It is likely that several biases, notably study design and prostate size at the time of biopsy, contributed to the numerical imbalance in Gleason 8-10 cancers observed between the treatment groups in years 3-4.

PMID:
24916669
DOI:
10.1016/j.urology.2014.04.016
[Indexed for MEDLINE]
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