The new ISUP grading system and its prognostic value

Back in June this year we provided an initial, basic introduction to the new, grouped, pathologic staging system approved by the International Society of Urologic Pathologists as a replacement for the Gleason grading system over the next few years. Apparently the intent is that the new system will be referred to simply as the “ISUP” grading system.

A newly published paper by an Australasian pathology group (Samaratunga et al.) appears to offer us the first instance of research into the practical utility of the new ISUP system.

The authors set out to conduct an independent examination of the predictive value of ISUP grading by comparing the results of using this grading system with other, recognized prognostic parameters.

To do this, they looked at clinical and pathologic data from 2,079 men who underwent a radical prostatectomy between 2008 and 2013, and for whom positive needle biopsy data were also available. In particular, they focused on the association between the patients’ ISUP grade on needle biopsy, the patients’ Gleason score (based on the 2005 modification to the Gleason scoring system), tumour volume, pathological stage of the actual surgical speciment, and the biochemical recurrence-free survival of the patients.

Here are their findings:

  • The average (median) age of the patients was 62 years (range, 32 to 79 years).
  • The average (median) serum PSA level of the patients was 5.9 ng/ml (range, 0.4 to 69  ng/ml).
  • The ISUP grades of the needle biopsy cores from the patients were:
    • Group 1 — 280/2,079 (13.5 percent)
    • Group 2 — 1,031/2,079 (49.6 percent)
    • Group 3 — 366/2,079 (17.6 percent)
    • Group 4 — 77/2,079 (3.7 percent)
    • Group 5 — 325/2,079 (15.6 percent)
  • The ISUP grade was significantly associated with
    • Tumor volume in the radical prostatectomy specimen (p  <  0.001)
    • pT and pN stage (p  <  0.001)
    • Biochemical recurrence-free survival (p  < 0.001).
  • On multivariate analysis it was apparent that, at time of diagnosis, patients’ PSA levels and an ISUP grade > 2 based on the needle biopsy speiments were also significantly associated with subsequent biochemical recurrence-free survival.

The authors conclude simply that their study

provides evidence of the prognostic significance of ISUP grading for thin core needle biopsy of prostate.

One Response

  1. It is worth noting that a second paper just published on line in Pathology (by Delahunt et al.), and also designed to validate the new ISUP grading system, concludes that the new ISUP grading system significantly out-performed the older 2005 modification of the Gleason grading system for each of the three clinical endpoints evaluated in that study.

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