Can MRI data improve older, pre-treatment, prognostic methods?


An obvious but previously unanswered question has been whether adding data from the results of MRI scans to the data used in the Partin tables and in the pre-surgical Kattan nomogram (also known as the Memorial-Sloan Kettering Cancer Center or MSKCC nomogram) can improve the accuracy of these two commonly used prognostic methods.

A recently published article by Jansen et al. in the journal Urologic Oncology has explored this question, and has come to the conclusion that the answer (at least based on the current quality of MRI data) is “No”.

Jansen et al. used the pre-treatment multiparametric MRI (mpMRI) data from 430 patients who were scheduled to undergo robot-assisted radical prostatectomies, together with the patients’ PSA data, clinical staging data, and pathological data from their diagnostic biopsies, to calculate four different sets of prognostic information for each of these 430 patients:

  • The Partin score
  • The Partin + mpMRI score
  • The Kattan/MSKCC score
  • The Kattan/MSKCC + mpMRI score

They then used these data to project the pre-treatment probability of extracapsular extension for each patient and compared these predictions to the actual surgical outcomes for all 430 patients.

What they found was the following:

  • Like the Partin and the Kattan/MSKCC scores, mpMRI data on its own was a significant predictor of risk for locally advanced prostate cancer, but …
  • When compared to the Kattan/MSKCC score alone, the Kattan/MSKCC + mpMRI score only improved prognostic accuracy by about 1 percent (from 0.73 to 0.74).
  • When compared to the Partin score alone, the Partin + mpMRI score only improved prognostic accuracy by about 4 percent (from 0.62 to 0.66).
  • These improvements in prognostic accuracy were not statistically significant.

The authors conclude that:

The addition of mpMRI to the preoperative MSKCC and Partin nomograms did not increase diagnostic accuracy for the prediction of locally advanced prostate cancer.

This may come as a surprise to many readers, but it probably shouldn’t. What this actually tells us is that the combination of PSA level, clinical stage, and pathological data from a patient’s diagnostic biopsy has been — and remains today — a highly accurate estimator of the probabilities of certain types of outcome after a radical prostatectomy. And bear in mind that it is these three sets of data that are customarily used to categorize patients today into one of the six standard “risk groups” defined by the National Comprehensive Cancer Network: very low risk, low risk, favorable intermediate risk, unfavorable intermediate risk, high risk, and very high risk.

These data also confirm the fact that the Kattan/MSKCC nomogram is about 10 percent more accurate than the Partin tables (also a not unexpected finding). mpMRI scanning may be measuring something very different from the historically useful data used to estimate risk for certain types of outcome after a radical prostatectomy, and may well help a patient and his doctor to decide what to do in thinking about treatment, but the the Kattan/MSKCC nomogram and the Partin tables remain an extremely useful set of tools for gaining an initial perspective on an individual’s outcome after radical prostatectomy.

The next unanswered question will be whether adding genomic data (e.g., from the Decipher or other similar genetic/genomic test) to the Kattan/MSKCC nomogram and/or the Partin tables can produce a more accurate set of prognostic information.

3 Responses

  1. It doesn’t surprise me. mpMRI is good at finding significant cancer, which biopsy confirms anyway — so the info is duplicated or is better from biopsy data. It is not very good at staging — better at seminal vesicle invasion (which is rare), worse at extracapsular extension.

  2. IMO, not doing an MRI prior to biopsy, is negligence.

    You need to biopsy suspicious areas,

  3. Dear Doug:

    With respect, doing an initial MRI prior to biopsy on a man with a rock-hard prostate on DRE is a pretty expensive and pointless exercise, and would certainly not qualify as “negligence”. The question of who does need and who does not need an MRI is not as cut and dried as you are suggesting. Furthermore, if we did MRIs on every man on Medicare who needed to have a biopsy each year, your federal taxes would need to go up significantly.

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