Faculty Bibliography

PURPOSE: Reported prostate specific antigen values may differ substantially among assays using Hybritech(R) or WHO standardization. The Beckman Coulter(R) Prostate Health Index and [-2]proPSA are newly approved serum markers associated with prostate cancer risk and aggressiveness. We studied the influence of assay standardization on these markers. MATERIALS AND METHODS: Prostate specific antigen, percent free prostate specific antigen and [-2]proPSA were measured using Hybritech calibration in 892 men from a prospective, multicenter study undergoing prostate biopsy. We calculated the Prostate Health Index using the equation, ([-2]proPSA/free prostate specific antigen) x PSA. Index performance characteristics for prostate cancer detection were then determined using recalculated WHO calibration prostate specific antigen values. RESULTS: The median Prostate Health Index was significantly higher in men with prostate cancer than in those with negative biopsies using WHO values (47.4 vs 39.8, p <0.001). The index offered improved discrimination of prostate cancer detection on biopsy (AUC 0.704) compared to percent free or total prostate specific antigen using the WHO calibration. CONCLUSIONS: The Prostate Health Index can be calculated using Hybritech or WHO standardized assays. It significantly improved prediction of the biopsy outcome over that of percent free or prostate specific antigen alone.

PURPOSE: Recent studies have identified genetic variants associated with increased serum prostate specific antigen concentrations and prostate cancer risk, raising the possibility of diagnostic bias. By correcting for the effects of these variants on prostate specific antigen, it may be possible to create a personalized prostate specific antigen cutoff to more accurately identify individuals for whom biopsy is recommended. Therefore, we determined how many men would continue to meet common biopsy criteria after genetic correction of their measured prostate specific antigen concentrations. MATERIALS AND METHODS: The genotypes of 4 single nucleotide polymorphisms previously associated with serum prostate specific antigen levels (rs2736098, rs10788160, rs11067228 and rs17632542) were determined in 964 healthy Caucasian volunteers without prostate cancer. Genetic correction of prostate specific antigen was performed by dividing an individual's prostate specific antigen value by his combined genetic risk. Analyses were used to compare the percentage of men who would meet commonly used biopsy thresholds (2.5 ng/ml or greater, or 4.0 ng/ml or greater) before and after genetic correction. RESULTS: Genetic correction of serum prostate specific antigen results was associated with a significantly decreased percentage of men meeting biopsy thresholds. Genetic correction could lead to a 15% or 20% relative reduction in the total number of biopsies using a biopsy threshold of 2.5 ng/ml or greater, or 4.0 ng/ml or greater, respectively. In addition, genetic correction could result in an 18% to 22% reduction in the number of potentially unnecessary biopsies and a 3% decrease in potentially delayed diagnoses. CONCLUSIONS: Our results suggest that 4 single nucleotide polymorphisms can be used to adjust a man's measured prostate specific antigen concentration and potentially delay or prevent unnecessary prostate biopsies in Caucasian men.

Prostate-specific antigen (PSA) velocity predicts the presence of prostate cancer on biopsy and a greater risk of prostate cancer death after radical treatment. A new variation on PSA velocity called the risk count was recently shown to provide incremental reclassification for intermediate to high-grade disease on biopsy beyond PSA and age. These markers therefore have the potential to reduce overdiagnosis and overtreatment of indolent prostate cancer, and several professional guidelines support the use of PSA kinetics along with other predictors as part of the diagnostic algorithm. Among men already diagnosed with prostate cancer, PSA kinetics may also be helpful in predicting prognosis after definitive therapy.

PURPOSE: While a clear heritable component underlies lower urinary tract symptoms and benign prostatic hyperplasia, few studies have identified specific genetic factors. In contrast, recent genome-wide association studies identified single nucleotide polymorphisms that increase prostate cancer risk. Some of these single nucleotide polymorphisms may also predispose to surgical intervention for benign prostatic hyperplasia. We determined whether these single nucleotide polymorphisms are also associated with lower urinary tract symptom severity and benign prostatic hyperplasia medication use. MATERIALS AND METHODS: The genotypes of 38 single nucleotide polymorphisms previously associated with prostate cancer risk were determined for 1,168 healthy white male volunteers. American Urological Association symptom index score and medication for benign prostatic hyperplasia were documented prospectively. Statistical analyses were done to compare the frequency of the single nucleotide polymorphisms with American Urological Association symptom index and benign prostatic hyperplasia medication use. RESULTS: Several single nucleotide polymorphisms, including rs2736098 on chromosome 5p15, showed a significant relationship with benign prostatic hyperplasia medication. After adjusting for the other genetic variants, patient age and medication use, rs1571801 on chromosome 9q33.2 (OR 1.31, 95% CI 1.0-1.74) and rs5945572 on chromosome Xp11 (OR 1.28, 95% CI 1.04-1.59) were significantly associated with increased urinary symptoms. In contrast, rs445114 on chromosome 8q24 was marginally associated with decreased urinary symptoms (OR 0.83, 95% CI 0.66-1.01). CONCLUSIONS: Of 38 single nucleotide polymorphisms that predispose to prostate cancer we identified 3 that are also associated with a well characterized lower urinary tract symptom phenotype. These single nucleotide polymorphisms may aid in the improved characterization of men with lower urinary tract symptoms/benign prostatic hyperplasia.

PURPOSE: We recently reported an increasing risk over time of hospitalization among Medicare participants after undergoing an initial prostate biopsy. Less is known about the relative risks of repeat prostate biopsies, which are frequently performed in prostate cancer screening and in active surveillance programs. We determined whether repeat biopsies are associated with an increased risk of hospitalization compared to the initial biopsy. MATERIALS AND METHODS: Using SEER (Surveillance, Epidemiology and End Results)-Medicare linked data from 1991 to 2007 we identified 13,883 men who underwent a single prostate biopsy and 3,640 who had multiple biopsies. The 30-day hospitalization rates were compared between these groups, and with a randomly selected control population of 134,977. ICD-9 codes were then used to examine the frequency of serious infectious and noninfectious urological complications as the primary diagnosis for hospital admissions. RESULTS: Initial and repeat biopsies were associated with a significantly increased risk of hospitalization within a 30-day period compared to randomly selected controls (p <0.0001). However, the repeat biopsy session was not associated with a greater risk of infectious (OR 0.81, 95% 0.49-1.32, p = 0.39) or serious noninfectious urological complications (OR 0.94, 95% CI 0.54-1.62, p = 0.82) compared to the initial biopsy. CONCLUSIONS: Each biopsy was associated with a significant risk of complications compared to randomly selected controls. However, the repeat biopsy procedure itself was not associated with a greater risk of serious complications requiring hospital admission compared to the initial biopsy.

PURPOSE: Prostate cancer (PCa) incidence and prognosis vary geographically. We examined possible differences in PCa risk by clinical risk category between native-born and immigrant populations in Sweden. Our hypothesis was that lower PSA-testing uptake among foreign-born men would result in lower rates of localized disease, and similar or higher risk of metastatic disease. METHODS: Using the Prostate Cancer database Sweden, we identified 117,328 men with PCa diagnosed from 1991 to 2008, of which 8,332 were foreign born. For each case, 5 cancer-free matched controls were randomly selected from the population register. Conditional logistic regression was used to compare low risk, intermediate risk, high risk, regionally metastatic, and distant metastatic PCa based upon region of origin. RESULTS: Across all risk categories, immigrants had significantly lower PCa risk than native-born Swedish men, except North Americans and Northern Europeans. The lowest PCa risk was observed in men from the Middle East, Southern Europe, and Asia. Multivariable adjustment for socioeconomic factors and comorbidities did not materially change risk estimates. Older age at immigration and more recent arrival in Sweden were associated with lower PCa risk. Non-native men were less likely to be diagnosed with PCa through PSA testing during a health checkup. CONCLUSIONS: The risk for all stages of PCa was lower among first-generation immigrants to Sweden compared with native-born men. Older age at immigration and more recent immigration were associated with particularly low risks. Patterns of PSA testing appeared to only partly explain the differences in PCa risk, since immigrant men also had a lower risk of metastatic disease.

PURPOSE OF REVIEW: To determine whether alpha-blockers, commonly used for the treatment of benign prostatic hyperplasia, are associated with prostate cancer risk. RECENT FINDINGS: Alpha-blockers have been associated with a reduced risk of prostate cancer aggressiveness in some observational studies and an increased risk in other studies. However, this relationship is complex as different alpha-blockers have divergent effects in laboratory studies and there are many confounders in daily practice such as differential screening practices. SUMMARY: Both benign prostatic hyperplasia and prostate cancer are common conditions in the aging male population, such that an interaction between alpha-blockers and prostate cancer risk is clinically relevant. Prospective evidence is necessary to establish a definitive link.