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Abstracts

LE Magazine January 2008
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PSA

Assessing prostate cancer risk: results from the Prostate Cancer Prevention Trial.

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 5,519 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 > or =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.

J Natl Cancer Inst. 2006 Apr 19;98(8):529-34

Interchangeability and diagnostic accuracy of two assays for total and free prostate-specific antigen: two not always related items.

The variation between different PSA assays seems to influence the interpretation of individual PSA values and the clinical decisions about prostate cancer. One reason for this variability could be the different reactivity of antibodies for the various molecular forms of serum PSA; as a result, samples containing the same amount of tPSA but different proportions of fPSA can produce very different values. In this study, serum samples were collected prospectively from 152 consecutive patients referred to 2 institutions (Regional Hospital, Venice, 90 subjects; San Bortolo Hospital, Vicenza, 62 subjects) for PSA elevation and/or symptoms. Serum samples were assessed according to the manufacturers’ instructions on the following 2 analyzers: the Immulite 2000 assay (Diagnostic Products Corporation, Los Angeles, USA), which measures tPSA and fPSA, and the ADVIA Centaur (Bayer Diagnostics, Tarrytown, USA), which assays tPSA and cPSA. cPSA values were transformed into fPSA by the equation fPSA=tPSA-cPSA. When taking Immulite tPSA and f/tPSA values as 100%, ADVIA Centaur values were 92.6% and 122%, respectively, which means that 20% of patients would be classified differently according to the traditional biopsy cutoff. In conclusion, there are considerable differences between the 2 methods, which could affect clinical decisions.

Int J Biol Markers. 2007 Apr-Jun;22(2):154-8

Biochemical (Prostate-Specific Antigen) Relapse: An Oncologist’s Perspective.

Consensus has not been reached on the exact definition of biochemical relapse after prostatectomy; individual institution definitions of relapse after prostatectomy range from consecutively rising prostate-specific antigen (PSA) values of > 0.2 to > 0.6 ng/mL. PSA measurements after radiation are even less predictable. PSA level is a sensitive marker of occult prostate-cancer relapse and provides early notification of recurrence, but a PSA relapse does not equal a clinical relapse or death from prostate cancer. Data are reviewed from retrospective, single-institution trials that have clarified features of PSA relapse after both prostatectomy and radiation, such as the PSA doubling time and the time to the first PSA elevation, which are associated with clinical progression. Various options for treatment of biochemical relapse are also reviewed; these include hormone therapy, combined chemohormonal therapy, alternative medicine and dietary tactics, new agents, and future strategies, such as vaccination. Currently, there is no standard treatment for biochemical failure with proven benefit in terms of quality of life, time to metastases, or survival. Current options include observation for patients with long PSA doubling times or comorbid medical issues and standard or nontraditional hormone therapy or a clinical trial for men who desire early therapy or who have rapid PSA doubling times (< 10-12 months). Trials combining the early use of chemotherapy with hormone therapy are promising. Patients should be encouraged to enroll in clinical trials to help establish standards of care.

Rev Urol. 2003;5 Suppl 2:S3-S13

The influence of finasteride on the development of prostate cancer.

BACKGROUND: Androgens are involved in the development of prostate cancer. Finasteride, an inhibitor of 5alpha-reductase, inhibits the conversion of testosterone to dihydrotestosterone, the primary androgen in the prostate, and may reduce the risk of prostate cancer. METHODS: In the Prostate Cancer Prevention Trial, we randomly assigned 18,882 men 55 years of age or older with a normal digital rectal examination and a prostate-specific antigen (PSA) level of 3.0 ng per milliliter or lower to treatment with finasteride (5 mg per day) or placebo for seven years. Prostate biopsy was recommended if the annual PSA level, adjusted for the effect of finasteride, exceeded 4.0 ng per milliliter or if the digital rectal examination was abnormal. It was anticipated that 60 percent of participants would have prostate cancer diagnosed during the study or would undergo biopsy at the end of the study. The primary end point was the prevalence of prostate cancer during the seven years of the study. RESULTS: Prostate cancer was detected in 803 of the 4,368 men in the finasteride group who had data for the final analysis (18.4%) and 1,147 of the 4,692 men in the placebo group who had such data (24.4%), for a 24.8% reduction in prevalence over the seven-year period (95% confidence interval, 18.6 to 30.6%; P<0.001). Tumors of Gleason grade 7, 8, 9, or 10 were more common in the finasteride group (280 of 757 tumors

[37.0%], or 6.4 percent of the 4,368 men included in the final analysis) than in the placebo group (237 of 1,068 tumors [22.2%], P<0.001 for the comparison between groups; or 5.1% of the 4,692 men included in the final analysis, P=0.005 for the comparison between groups). Sexual side effects were more common in finasteride-treated men, whereas urinary symptoms were more common in men receiving placebo. CONCLUSIONS: Finasteride prevents or delays the appearance of prostate cancer, but this possible benefit and a reduced risk of urinary problems must be weighed against sexual side effects and the increased risk of high-grade prostate cancer. Copyright 2003 Massachusetts Medical Society

N Engl J Med. 2003 Jul 17;349(3):215-24

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