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We read with interest the article of Beer et al,1 which shows that elevated plasma C-reactive protein (CRP) concentrations appear to be a strong predictor of poor survival in men with prostate cancer. We performed a 1-year retrospective analysis (June 2007-June 2008), on the database of our Laboratory Information System, to retrieve combined results of CRP and prostate-specific antigen (PSA) performed on outpatients aged older than 35 years who had been referred to our laboratory by general practitioners for PSA screening. Patients were clustered according to their PSA value.2 Significance of differences between groups was assessed by the Wilcoxon-Mann-Whitney test (for continuous variables) and the chi-square test (for categorical variables). After being adjusted for age, associations between PSA and CRP were also assessed by using linear regression analysis.

Cumulative results (geometric mean ± standard error of the mean) were retrieved for 302 outpatients. The concentration of CRP was significantly increased in outpatients whose PSA was >2.5 ng/mL compared with those whose PSA was <2.5 ng/mL (5.9 ± 8.4 vs 2.5 ± 1.6 mg/dL; P = .001). Moreover, the prevalence of patients with increased CRP levels (>5.0 mg/dL) was higher in outpatients whose PSA was >2.5 ng/mL compared with those whose PSA was below this threshold (50% vs 33%; P < .001). In linear regression analysis, CRP was positively associated with PSA in the entire study population (standardized beta coefficient = .477; P < .001), in patients whose PSA was >2.5 ng/mL (standardized beta coefficient = .586; P < .001) but not in those whose PSA was <2.5 ng/mL (standardized beta coefficient = .059; P = .810).

The results of this retrospective epidemiological analysis show that CRP levels are strongly associated with increased values of PSA in a general population of outpatients undergoing PSA screening. Although no clinical data are available for these patients, we suggest the existence of an intriguing mutual relation between PSA and CRP, in that patients with increased PSA tend to have increased CRP values, which, in turn, may predispose patients with prostate cancer to a worse outcome.

References

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  • 1
    Beer TM,Lalani AS,Lee S, et al. C-reactive protein as a prognostic marker for men with androgen-independent prostate cancer: results from the ASCENT trial. Cancer. 2008; 112: 2377-2383.
  • 2
    Gilbert SM,Cavallo CB,Kahane H, et al. Evidence suggesting PSA cutpoint of 2.5 ng/mL for prompting prostate biopsy: review of 36,316 biopsies. Urology. 2005; 65: 549-553.

Giuseppe Lippi MD*, Martina Montagnana MD*, Gian Cesare Guidi MD*, * Sezione di Chimica Clinica, Dipartimento di Scienze Morfologico-Biomediche, Università di Verona, Italy.