Low Gleason score does not guarantee low-risk prostate cancer
MedWire News: Prostate cancer patients who have a low Gleason score (GS) at biopsy do not always have low-risk disease, say researchers.
Their findings indicate that GS should not be used as the only factor to assess disease risk in newly diagnosed prostate cancer patients, since high-risk patients with a GS of less than 3+3 can have a similar risk profile to patients with worse GSs.
“Our findings clearly show that there are important differences in the rates of extraprostatic disease and biochemical recurrence (BCR) among patients with GS ≤3+3 disease, according to the number and the percentage of positive biopsy cores,” say Hendrik Isbarn (Prostate Cancer Center Hamburg-Eppendorf, Germany) and fellow researchers in the BJU International .
The team defined overall favorable-risk disease, in line with previous US research, as GS less than or equal to 3+3, prostate-specific antigen (PSA) levels of less than 10 ng/ml, and a clinical stage of less than T2a.
Using data from 848 untreated prostate cancer patients, the researchers divided patients with GS 3+3 into two groups; low-risk (two or fewer positive biopsy cores) and high-risk (three or more positive biopsy cores).
The researchers then compared pathologic features and BCR rates of GS 3+3 patients with 258 patients whose clinical features were the same but whose GS was 3+4.
As not all patients had the same number of biopsy cores, the researchers subsequently stratified risk according to the percentage of positive biopsy cores.
The results show that rates of extracapsular extension and seminal vesicle invasion and/or pT4 disease in high-risk GS ≤3+3 patients were not significantly different from the comparison group of GS 3+4 patients, at 17.0% versus 23.3%, and 6.3% versus 11.7%, respectively.
Similarly, 5-year BCR-free survival rates for high-risk GS ≤3+3 patients and GS 3+4 patients were not significantly different at 77.8% versus 81.2%.
When percentage of positive biopsy cores was used for comparison, 5-year BCR-free survival rates were still comparable; patients with GS ≤3+3 and more than 50% positive biopsy cores had similar results to patients with GS 3+4 and less than 50% positive cores (77.8% versus 78.6%).
The researchers conclude that staging schemes and prediction tools can be useful but “should be interpreted with caution, as the presence of GS ≤3+3 disease does not invariably imply the presence of indolent cancer.”
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By Sarah Guy