An international multicenter study evaluating the impact of an alternative biochemical failure definition on the judgment of prostate cancer risk

Williams, Scott G., Duchesne, Gillian M., Gogna, N. Kumar, Millar, Jeremy L., Pickles, Tom, Pratt, Gary R. and Turner, Sandra (2006). An international multicenter study evaluating the impact of an alternative biochemical failure definition on the judgment of prostate cancer risk. In: International Journal of Radiation: Oncology • Biology • Physics. RANZCR 2005 ASM: 56th Annual Scientific Meeting of the Royal Australian and New Zealand College of Radiologists, Sydney, NSW, Australia, (351-357). 6-9 October 2005. doi:10.1016/j.ijrobp.2005.12.007


Author Williams, Scott G.
Duchesne, Gillian M.
Gogna, N. Kumar
Millar, Jeremy L.
Pickles, Tom
Pratt, Gary R.
Turner, Sandra
Title of paper An international multicenter study evaluating the impact of an alternative biochemical failure definition on the judgment of prostate cancer risk
Conference name RANZCR 2005 ASM: 56th Annual Scientific Meeting of the Royal Australian and New Zealand College of Radiologists
Conference location Sydney, NSW, Australia
Conference dates 6-9 October 2005
Convener Royal Australian and New Zealand College of Radiologists (RANZCR)
Proceedings title International Journal of Radiation: Oncology • Biology • Physics   Check publisher's open access policy
Journal name International Journal of Radiation Oncology Biology Physics   Check publisher's open access policy
Place of Publication Tarrytown, NY, U.S.A.
Publisher Elsevier
Publication Year 2006
Sub-type Fully published paper
DOI 10.1016/j.ijrobp.2005.12.007
ISSN 0360-3016
1879-355X
Volume 65
Issue 2
Start page 351
End page 357
Total pages 7
Language eng
Formatted Abstract/Summary
Purpose
To evaluate the impact of an alternative biochemical failure (bF) definition on the performance of existing plus de novo prognostic models.

Methods and Materials
The outcomes data of 1,458 Australian and 703 Canadian men treated with external-beam radiation monotherapy between 1993 and 1997 were analyzed using a lowest prostate-specific antigen (PSA) level to date plus 2 ng/mL (L + 2) bF definition. Two existing prognostic models were scrutinized using discrimination (Somers Dxy [SDxy]) and calibration indices. Alternative prognostic models were also created using recursive partitioning analysis (RPA) and multivariate nomogram methods for comparison.

Results
Discrimination of bF was improved using the L + 2 definition compared with the American Society for Therapeutic Radiology and Oncology (ASTRO) definition using both the three-level risk model (SDxy 0.30 and 0.22, respectively) or the nomogram (SDxy 0.35 and 0.27, respectively). Both existing prognostic models showed only modest calibration accuracy. Using RPA, five distinct risk groups were identified based primarily on Gleason score (GS) and all subsequent divisions based on PSA. All GS 7–10 tumors were intermediate or high risk. This model and the developed nomogram showed improved discrimination over the existing models as well as accurate calibration against the Canadian data, apart from the 30–50% failure region.

Conclusions
The L + 2 definition of bF provides improved capacity for discrimination of failure risk. New prognostic models based on this endpoint have overall statistical performance superior to those based on the ASTRO consensus definition but continue to have unreliable discrimination in the intermediate-risk region.
© 2006 Elsevier Inc.
Subjects 1103 Clinical Sciences
1112 Oncology and Carcinogenesis
Keyword Prostate cancer
Radiotherapy
Biochemical outcome
Prognostic factors
Q-Index Code EX
Additional Notes Published under "Clinical Investigation: Prostate".

 
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Created: Fri, 16 Apr 2010, 13:35:57 EST by Jon Swabey on behalf of Faculty Of Health Sciences