New Predictive Model To Assess Individual's Risk Of Prostate Cancer
April 21, 2006. Researchers have developed a model to predict prostate cancer for men who undergo a prostate biopsy. The details of the risk calculator appear in the April 18 issue of the Journal of the National Cancer Institute.
Fifty percent of men in the United States undergo regular screening for prostate cancer, using a test that measures levels of prostate-specific antigen (PSA), a protein secreted by the prostate gland. However, recent research looking at PSA levels after a prostate biopsy has revealed that PSA level is not a very accurate predictor of prostate cancer risk. Prostate cancer can occur when PSA levels are "normal." Other variables, such as family history, age, race, and digital rectal examination (DRE) results also play a role in assessing prostate cancer risk.
To better assess prostate cancer risk, Ian M. Thompson, M.D., of the University of Texas Health Science Center at San Antonio, and colleagues analyzed information on 5519 men aged 55 or older from the placebo group of the Prostate Cancer Prevention Trial (PCPT).
Men in the PCPT were followed for 7 years, receiving regular PSA screening and DREs annually. If tests were abnormal, men underwent a prostate biopsy to check for prostate cancer. Men also underwent biopsies at the end of the study if they had not undergone a biopsy during the study. The researchers used various statistical tests to analyze biopsy results, family history of prostate cancer, race, age, rectal examination results, and previous biopsy history.
The authors used the equations generated by their analysis to develop a risk calculator that can be used to assess an individual's risk of prostate cancer. The risk calculator is available online and can be used to calculate risk of prostate cancer and high-grade disease for men aged 50 years or and older who have no previous history of prostate cancer and who have had recent PSA screening and DRE tests.
The authors write, "This risk calculator model uses variables that go beyond only PSA level to help patients and physicians decide whether a prostate biopsy should be performed. We anticipate that the area of cancer risk modeling -- including the incorporation of new risk variables and the understanding of patient decision-making -- will have a measurable clinical impact over the next few years."
In an accompanying editorial, H. Ballentine Carter, M.D., of the Johns Hopkins School of Medicine in Baltimore, brings up concerns about over treatment of prostate cancer if the model were to pick up the non-lethal varieties of prostate cancer. He writes:
In the absence of accurate markers of life-threatening disease, I do not believe that physicians should endorse any approach to predicting the risk of prostate cancer that is likely to increase the diagnosis of biologically unimportant cancers. Once we have the ability to assess multiple risk factors (e.g., PSA or other new markers) in populations for which the long-term outcomes are known, approaches like the one described by Thompson, et al. will help identify those men who will benefit from active treatment.
Sources and links
Article: Thompson IM, Ankerst DP, Chen C, Goodman PJ, Tangen CM, Lucia MS, et al. Assessing Prostate Cancer Risk: Results from the Prostate Cancer Prevention Trial. J Natl Cancer Inst 2006; 98:529-534.
Editorial: Carter HB. Assessing Risk: Does This Patient Have Prostate Cancer? J Natl Cancer Inst 2006; 98:506-507.
Abstract:
Assessing Prostate Cancer Risk: Results from the Prostate Cancer Prevention Trial
Ian M. Thompson , Donna Pauler Ankerst , Chen Chi , Phyllis J. Goodman , Catherine M. Tangen , M. Scott Lucia , Ziding Feng , Howard L. Parnes , Charles A. Coltman, Jr.
Affiliations of authors: Department of Urology, University of Texas Health Science Center, San Antonio, TX (IMT); The Fred Hutchinson Cancer Research Center, Seattle, WA (DPA, CC, PJG, CMT, ZF); University of Colorado, Denver, CO (MSL); Division of Cancer Prevention, National Cancer Institute, Bethesda, MD (HLP); Southwest Oncology Group, San Antonio, TX (CAC)
Correspondence to: Ian Thompson, MD, Department of Urology, UTHSCSA, University of Texas HSC at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX 78229 .
Background: Prostate-specific antigen (PSA) testing is the primary method used to diagnose prostate cancer in the United States. Methods to integrate other risk factors associated with prostate cancer into individualized risk prediction are needed. We used prostate biopsy data from men who participated in the Prostate Cancer Prevention Trial (PCPT) to develop a predictive model of prostate cancer.
Methods: We included 5519 men from the placebo group of the PCPT who underwent prostate biopsy, had at least one PSA measurement and a digital rectal examination (DRE) performed during the year before the biopsy, and had at least two PSA measurements performed during the 3 years before the prostate biopsy. Logistic regression was used to model the risk of prostate cancer and high-grade disease associated with age at biopsy, race, family history of prostate cancer, PSA level, PSA velocity, DRE result, and previous prostate biopsy. Risk equations were created from the estimated logistic regression models. All statistical tests were two-sided.
Results: A total of 1211 (21.9%) men were diagnosed with prostate cancer by prostate biopsy. Variables that predicted prostate cancer included higher PSA level, positive family history of prostate cancer, and abnormal DRE result, whereas a previous negative prostate biopsy was associated with reduced risk. Neither age at biopsy nor PSA velocity contributed independent prognostic information. Higher PSA level, abnormal DRE result, older age at biopsy, and African American race were predictive for high-grade disease (Gleason score 7) whereas a previous negative prostate biopsy reduced this risk. Conclusions: This predictive model allows an individualized assessment of prostate cancer risk and risk of high-grade disease for men who undergo a prostate biopsy.
Note: The Journal of the National Cancer Institute is published by Oxford University Press and is not affiliated with the National Cancer Institute.
Related
PSA Endpoints May Speed Prostate Cancer Research April 19, 2006
Low PSA Nadir and Longer Time to Nadir After Radiation Can Predict Freedom From Prostate Cancer Return March 16, 2006
This page made and last edited by J. Strax, April 21, 2006.
Information on this website is not intended as medical advice nor to be taken as such. Consult qualified physicians specializing in the treatment of prostate cancer. Neither the editors nor the publisher accepts any responsibility for the accuracy of the information or consequences from the use or misuse of the information contained on this website.
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