Can urinary testing of prostate cancer–associated RNA (PCA3 and TMPRSS2:ERG) improve detection of aggressive prostate cancer (Gleason score, ≥7), and how would such testing affect health care costs?
In this prospective diagnostic study of 1077 men, urinary RNA parameters that significantly improved specificity for predicting prostate cancer were identified in the developmental cohort and improvement of specificity for predicting aggressive cancer (33% vs 17%) was confirmed in a validation cohort. Potential health care cost savings were shown by modeling the effect of urinary PCA3 and TMPRSS22:ERG testing.
Urinary testing for TMPRSS2:ERG and PCA3 can avert unnecessary biopsy with consequent potential health care cost savings.
Potential survival benefits from treating aggressive (Gleason score, ≥7) early-stage prostate cancer are undermined by harms from unnecessary prostate biopsy and overdiagnosis of indolent disease.
To evaluate the a priori primary hypothesis that combined measurement of PCA3 and TMPRSS2:ERG (T2:ERG) RNA in the urine after digital rectal examination would improve specificity over measurement of prostate-specific antigen alone for detecting cancer with Gleason score of 7 or higher. As a secondary objective, to evaluate the potential effect of such urine RNA testing on health care costs.
Design, Setting, and Participants
Prospective, multicenter diagnostic evaluation and validation in academic and community-based ambulatory urology clinics. Participants were a referred sample of men presenting for first-time prostate biopsy without preexisting prostate cancer: 516 eligible participants from among 748 prospective cohort participants in the developmental cohort and 561 eligible participants from 928 in the validation cohort.
Urinary PCA3 and T2:ERG RNA measurement before prostate biopsy.
Main Outcomes and Measures
Presence of prostate cancer having Gleason score of 7 or higher on prostate biopsy. Pathology testing was blinded to urine assay results. In the developmental cohort, a multiplex decision algorithm was constructed using urine RNA assays to optimize specificity while maintaining 95% sensitivity for predicting aggressive prostate cancer at initial biopsy. Findings were validated in a separate multicenter cohort via prespecified analysis, blinded per prospective-specimen-collection, retrospective-blinded-evaluation (PRoBE) criteria. Cost effects of the urinary testing strategy were evaluated by modeling observed biopsy results and previously reported treatment outcomes.
Among the 516 men in the developmental cohort (mean age, 62 years; range, 33-85 years) combining testing of urinary T2:ERG and PCA3 at thresholds that preserved 95% sensitivity for detecting aggressive prostate cancer improved specificity from 18% to 39%. Among the 561 men in the validation cohort (mean age, 62 years; range, 27-86 years), analysis confirmed improvement in specificity (from 17% to 33%; lower bound of 1-sided 95% CI, 0.73%; prespecified 1-sided P = .04), while high sensitivity (93%) was preserved for aggressive prostate cancer detection. Forty-two percent of unnecessary prostate biopsies would have been averted by using the urine assay results to select men for biopsy. Cost analysis suggested that this urinary testing algorithm to restrict prostate biopsy has greater potential cost-benefit in younger men.
Conclusions and Relevance
Combined urinary testing for T2:ERG and PCA3 can avert unnecessary biopsy while retaining robust sensitivity for detecting aggressive prostate cancer with consequent potential health care cost savings.
Sanda MG, Feng Z, Howard DH, Tomlins SA, Sokoll LJ, Chan DW, Regan MM, Groskopf J, Chipman J, Patil DH, Salami SS, Scherr DS, Kagan J, Srivastava S, Thompson IM, Siddiqui J, Fan J, Joon AY, Bantis LE, Rubin MA, Chinnayian AM, Wei JT, and the EDRN-PCA3 Study Group. Association Between Combined TMPRSS2:ERG and PCA3 RNA Urinary Testing and Detection of Aggressive Prostate Cancer. JAMA Oncol. Published online May 18, 2017. doi:10.1001/jamaoncol.2017.0177