Have reported patterns of Gleason scores changed significantly since 2005?


It has frequently been postulated that the recommendations of the International Society of Urological Pathology (ISUP) consensus meeting in 2005 would lead to a gradual “upgrading” of all pathologically evident prostate cancers.

Effectively, the ISUP consensus meeting of 2005 made two key recommendations:

  • Patients with Gleason scores of 2 to 5 should no longer be reported as having clinically meaningful evidence of cancer.
  • Any cancerevidence of cancer that the pathologist considered as being clinically meaningful should be classified as at least Gleason 3 + 3 = 6.

In Sweden, data related to all newly diagnosed cases of prostate cancer must be reported to the Swedish National Prostate Cancer Register (NPCR), and these data include the patients’ Gleason scores, their clinical stages, and their serum PSA levels at diagnosis. The NPCR has been collecting and collating such data since 1998.

Danneman et al. have now reported on changes in patterns of Gleason scores being reported to the NPCR from 1998 to 2011. Here is a summary of their findings:

  • 97,168 cases of patients with a primary diagnosis of prostate cancer on needle biopsy were reported to the NPCR between 1998 and 2011.
    • Gleason scores were available for 97 percent of these patients.
    • Clinical T stages were available for 99 percent of these patients.
    • Serum PSA levels were available for 99 percent of these patients.
  • When all patients were considered
    • Gleason scores of 7 to 10 were reported for 52 percent of patients before 2005.
    • Gleason scores of 7 to 10 were reported for 57 percent of patients after 2005.
  • Among patients with low-risk tumors (clinical stage T1c; PSA level of 4 to 10 ng/ml)
    • Gleason scores of 7 to 10 were reported in 16 percent of patients in 1998 (baseline level).
    • Gleason scores of 7 to 10 were reported in 40 percent of patients in 2011.
    • Gleason scores of 7 to 10 were reported in an average (mean) of 19 percent of patients per year before 2005.
    • Gleason scores of 7 to 10 were reported in an average of 33 percent of patients per year after 2005.
  • Among patients with high-risk tumors (clinical stage T3; PSA level of 20 to 50 ng/ml)
    • Gleason scores of 7 to 10 were reported in 65 percent of patients in 1998 (baseline level).
    • Gleason scores of 7 to 10 were reported in 94 percent of patients in 2011.
    • Gleason scores of 7 to 10 were reported in an average of 78 percent of patients per year before 2005.
    • Gleason scores of 7 to 10 were reported in an average of 90 percent of patients per year after 2005.
  • Gleason scores of 2-5 were reported in
    • 27 percent of patients in 1998
    • 1 percent of patients in 2011
  • Reporting of Gleason scores of 5 decreased sharply after 2005.
  • Reporting of Gleason scores of 2 to 4 were almost completely abandoned after 2005.

The last two of the above-mentioned results are, in fact, in complete alignment with the recommendations of the ISUP consensus recommendations, and were therefore predictable. However, some of the other results above-mentioned are harder to interpret.

If cases of prostate cancer with Gleason grades of 2 to 5 were no longer to be reported as being clinically significant, pathologists often had to make a decision: Did the evidence of cancer that was present justify grading of the cancer as Gleason 6? Any pathological finding that did not rise to that level inevitably reduced the total number of cancers being reported. However, the abstract of the paper by Danneman et al. does not tell us whether there was an overall decrease in the numbers of low-risk cancers diagnosed per year after 2005. A decrease in the number of cancers actually being diagnosed by pathologic evidence on biopsy would inevitably result in an increase in the percentage of cancers diagnosed that were categorized as Gleason 7 to 10.

What is therefore not clear from the data in the abstract is whether the absolute average increases of 14 percent (for men with low-risk disease) and 12 percent (for men with high-risk disease) among men being classified as having Gleason scores of 7 to 10 after 2005 can be accurately attributed to a decline in the number of cases of prostate cancer being diagnosed or whether there is a real upward shift in the classification of patients according to Gleason score after 2005.

What are certainly true are two other points made by Danneman et al. in their conclusions:

  • Pathological grading systems need to be as stable as possible over time to enable comparisons and to facilitate the interpretation of the prognostic impact of patient grade at diagnosis.
  • Any significant upward shift in assignment of Gleason scores over time does have very real clinical consequences for therapy decisions (e.g., eligibility for active surveillance).

Given the apparent rise in the frequency of Gleason scores of 7 to 10 over time since 2005,

  • From a mean of 33 percent for the period 2005 to 2011 to 40 percent in 2011 for low-risk patients
  • From a mean of 90 percent for the period 2005 to 2011 to 94 percent in 2011 for high-risk patients

it does seem as though — at least in Sweden — there is a continuing and gradual upward creep in the assigned Gleason grades and scores of newly diagnosed patients. This raises the interesting question of whether the (Swedish) pathology community is feeling pressure to identify as clinically significant tumors cellular patterns that would not have been so identified prior to 2005. We do know that, at least in Sweden, there is no good legal reason to explain such a pressure. The situation might be very different here in the USA, where failure to appropriately identify cancer on a pathological slide might well have serious legal consequences.

2 Responses

  1. Another change in 2005 was that most cribriform pattern 3 would be re-classified as cribriform pattern 4. This would increase the diagnosis of Gleason score 7s at the expense of Gleason score 6s, while lowering the risk associated with both by the Will Rogers Effect.

  2. This study might show that either (1) pathology is not an exact science (not a new revelation) or (2) today’s pathologists are getting smarter (young people would like this explanation) or (3) prostate cancer is becoming a more aggressive disease in general and the upgrading of Gleason scores represents some genetic change in the cancer as it occurs in the population (scary).

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