Rotterdam Prostate Cancer Risk Calculator app

The widespread use of prostate specific antigen (PSA) testing has led to diagnostic difficulties for patients and urologists. The sensitivity and specificity characteristics of PSA are far from optimal. To try and improve the predictive accuracy of PSA measurements, nomograms and artificial neural networks have been created by many groups across the world1. By combining PSA measurements with various examination and investigation findings these predictive models have shown to be superior to PSA alone1.  Initially these models were available as paper-based nomograms or as calculators via the internet but now this form of prediction can be produced on any smartphone or tablet via an app.

Rotterdam Prostate Cancer Risk Calculator

The Rotterdam Prostate Cancer Risk Calculator app was released through the Prostate Cancer Research Foundation, Rotterdam, in partnership with the European Randomized Study of Screening for Prostate Cancer (ERSPC). The tool can be accessed as a smartphone or tablet app, available on Android or iOS (£1.49), or via a series of calculators at http://www.prostatecancer-riskcalculator.com.DSC01144

The website version of the risk calculators are meant for use as a decision aid for laypeople, general practitioners and urologists2. On the website there are 6 calculators. These calculators provide an estimate of risk of sextant biopsy detectable prostate cancer based upon age, family history, and urinary complaints (calculator 1), PSA alone (calculator 2). Calculators 3-6 are designed for use by urologists and require more complex information such as DRE findings and volume, TRUS findings and volume and previous biopsy status.

The mobile application was developed to improve the user friendliness and accessibility of the calculators and combines a lot of the previous calculators into one easy to use application3. The values that the calculator uses include PSA, Previous biopsy negative, DRE examination findings, TRUS volume and TRUS findings and Phi (if available). If the patient has not had a TRUS than volume can be estimated according to DRE findings instead.

Screenshot_2014-05-11-20-39-01Does this apply to my patients?

The data for the RPCRC was gathered from the Dutch section of the ERSPC, and are based on a population aged 55-74 yr. The analyses are based on the biopsy outcomes of 3616 men screened for the first time, 24.5% of whom had prostate cancer detected. A further cohort of 2896 men was used to compile data on those men who had previously been screened, 34.1% of these men already had negative biopsies at first screening. Although the risk calculator has yet to be validated in a UK population it has been validated in a small contemporary clinical cohort despite significant differences between the screening group and the clinical cohort 4.

Is it better than PSA and DRE?

Recently published data at the 29th Annual EAU Congress in Stockholm shows that the more data that are provided pre-biopsy the more accurate the application is in predicting prostate cancer on biopsy3.  At initial screening the RPCRC  area under curve is significantly better than PSA and DRE (0.79 vs 0.73 respectively) for predicting prostate cancer and this effect is repeated for detecting serious prostate cancer. In those who have had a previous PSA test and or biopsy a similar effect is seen (0.69 vs 0.64 respectively).

What information does the calculator provide?

The calculator provides the detectable prostate cancer risk as a percentage. The risk is given as a score for detectable prostate cancer and for significant prostate cancer. Significant prostate cancer is defined as tumour stage greater than T2b, and/or having a Gleason biopsy score of equal to or greater than 7. The percentage risk of prostate cancer leads to the following recommended actions:

  • <12.5% – no prostate biopsy
  • 12.5% – 20% – consider prostate biopsy depending on co-morbidity and more than average risk of high grade prostate cancer (>4%)
  • 20% or more – prostate biopsy recommendedScreenshot_2014-05-11-20-39-42

Should you ever forget this information; it is easily accessed within the app, by touching the encircled question mark, under the percentage risks.

Conclusion

Although there is a paucity of studies to externally validate the RPCRC app it provides robust data from a large cohort of men which are likely genetically similar to the UK population. The app is well thought out, easy to use in any outpatient clinic and provides a clear recommendation for further investigation. I would recommend the RPCRC app as an essential tool for all urologists and any practitioners involved in PSA assessment.

References

  1. Schröder F, Kattan MW. The Comparability of Models for Predicting the Risk of a Positive Prostate Biopsy with Prostate-Specific Antigen Alone: A Systematic Review. Eur Urol. 2008 Aug;54(2):274–90.
  2. Clarke NW. Coming Up for Air: Follow-up and Risk Stratification After Negative Prostate Cancer Screening. Eur Urol. 2013 Apr;63(4):634–5.
  3. Roobol MJ, van Vugt HA, Loeb S, Zhu X, Bul M, Bangma CH, et al. Prediction of prostate cancer risk: the role of prostate volume and digital rectal examination in the ERSPC risk calculators. Eur Urol. 2012 Mar;61(3):577–83.
  4. Roobol M. The Rotterdam prostate cancer risk calculator: Improved prediction with more relevant pre-biopsy information, now in the palm of your hand. Azevedo N, Salman J, editors. 2014; Available from: http://www.uroweb.org/index.php?id=108&AID=49681
  5. Van Vugt HA, Kranse R, Steyerberg EW, van der Poel HG, Busstra M, Kil P, et al. Prospective validation of a risk calculator which calculates the probability of a positive prostate biopsy in a contemporary clinical cohort. Eur J Cancer Oxf Engl 1990. 2012 Aug;48(12):1809–15.

Author

Ivo Dukic, ST7 in Urology, Tweet @urolsurg

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