End of Unnecessary Biopsies? Prostate Health Index (PHI) in Detecting Aggressive Carcinoma
The Prostate Health Index (PHI) combines the results of three blood-derived parameters: total PSA (tPSA), free PSA (fPSA), and [-2]proPSA (p2PSA) into a single numerical score: PHI = (p2PSA / fPSA × √tPSA). It is a marker used to differentiate patients indicated for prostate biopsy, enabling prediction of cancer aggressiveness and helping to choose the optimal course of action for a particular patient. Its benefit in distinguishing aggressive prostate cancer from indolent tumors or benign lesions was already proven in 2015.
Study Methodology
The ability of PHI to capture patients with aggressive prostate cancer was evaluated in a prospective American study, in two cohorts of men from various centers indicated for primary prostate biopsy. The authors compared the diagnostic specificity of PHI, tPSA, and %fPSA values determined before biopsy according to biopsy results. They also determined the threshold value of PHI to differentiate aggressive tumors defined as having a Gleason score (GS) ≥ 7.
Results
The primary cohort consisted of 561 men. Higher PHI values significantly correlated with tumor aggressiveness: the mean PHI was 74.6 ± 68.2 in patients with GS ≥ 7 and 32.2 ± 18.9 in men with GS ≤ 6. At 95% sensitivity, PHI's specificity for detecting aggressive tumors was 36.0% compared to 17.2% for tPSA and 19.4% for %fPSA. The optimal threshold for detecting aggressive tumors at 95% sensitivity was set at 24. Using PHI avoided 41% of unnecessary biopsies.
The validation cohort included 395 men. The results were similar: the mean PHI was 59.8 ± 50.5 in the GS ≥ 7 group compared to 31.6 ± 13.8 in the GS ≤ 6 group. The number of biopsies using the PHI with a threshold of 24 decreased by 36% with a small number of missed aggressive tumors.
Conclusion
The authors concluded that PHI is a suitable tool in diagnosing prostate cancer, reducing the number of unnecessary prostate biopsies.
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Source: de la Calle C., Patil D., Wei J. T. et al. Multicenter evaluation of the Prostate Health Index to detect aggressive prostate cancer in biopsy naïve men. J Urol 2015; 194 (1): 65−72, doi: 10.1016/j.juro.2015.01.091.
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