The GEMCaP markers and the Kattan post-surgical nomogram

There is increasing concurrence that the addition of GEMCaP biomarker data may be able to improve the prognostic accuracy of the Kattan post-treatment nomogram.

The Kattan post-surgical nomogram was initially developed by Kattan et al. in 1999 and an upgraded version of this nomogram was developed by Stephenson et al. in 2005. In January this year, Paris et al. reported their belief that the addition of data from a group of biomarkers known as the GEMCaP biomarkers (which appear to have specific relevance to prostate cancer progression) may be able to extend the predictive performance of the current version of the Kattan post-surgical nomogram.

In a commentary in “Beyond the Abstract” on the UroToday web site. Dr. Kattan himself has now endorsed the potential of this concept.

The current version of the Kattan post-surgical nomogram has two specific uses:

  • It can be used to support patient counseling for those patients who want a clear idea of their prognosis after surgery as first-line treatment.
  • It can be used to assist in the identification of those patients who need immediate adjuvant therapy (because it predicts how well the patient will do if adjuvant therapy is not provided)

However, the current post-surgical nomogram does not predict perfectly and needs improvement. For example, it is not clear (yet) whether the enhancements introduced by Stephenson et al. offer real improvements in predictive accuracy.

As Kattan carefully notes in his commentary, Paris et al. were able to look at data on the use of three different versions of  the so-called Genomic Evaluators of Metastatic Prostate Cancer (the GEMCaP biomarkers). They showed that two of the three versions of the GEMCaP biomarkers appeared to improve the predictive accuracy of the Kattan post-surgical nomogram. However, they were only working from a relatively small database, so more research will be essential before we can determine with certainty that adding GEMCaP data will truly improve the predictive accuracy of the current Kattan nomogram.

As Kattan himself writes, “If future research is able to show this, and the alteration in predicted probabilities from these types of models is clinically significant, GEMCaP might be a very valuable addition to our ability to predict progression probabilities.” In the interim , however, we will have to exert patience while we wait to see if this addition of genomic data to clinical data (the pretreatment serum PSA level, the Gleason score of cancer tissues in the pathologic specimen, capsular invasion, surgical margin status, seminal vesicle invasion, and lymph node status) really can lead to greater prognostic accuracy over time.

[Editorial note: To read Dr. Kattan’s original commentary you need to be a member of the UroToday information service, but there is not cost associated with membership.]

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