Session: MP40: Prostate Cancer: Detection & Screening I
MP40-11: Contribution of Gleason pattern 4 prostate cancer tissue to pre-operative PSA values in intermediate risk Prostate Cancer: Results from 4 860 RP specimens
Martini-Klinik Prostate Cancer Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
Introduction: Despite advances in imaging and genetic testing, blood PSA remains the cornerstone of prostate cancer (PCa) diagnosis and risk stratification. Especially in the management of intermediate-risk PCa, the PSA value has strong implications for clinical decision-making. It is known, that within this group Gleason pattern (GP) 4 drives biological aggressiveness. Aim of our study was to assess the relationship between pre-operative blood PSA values and volume of GP 4 compared to GP 3 and benign tissue in Radical Prostatectomy (RP) specimens. Methods: Overall, 4860 patients with localized pT2pN0cM0, intermediate risk PCa without tertiary GP were assessed. Individual GPs were quantified at the whole-mount section analysis of RP specimen. For analysis, patients with biochemical recurrence after RP and a pre-operative PSA >50ng/ml were further excluded for avoiding contamination of the cohort by occult metastasis. Moreover, patients with prior / neoadjuvant treatment, a gland size < 10cc after TUR-P or gland size > 150cc (associated risk of chronic inflammation) were excluded. Multivariable linear regression analysis addressed the relationship between volume of tissue types and PSA values. Results: Of 4860 patients, in 4390 (90%) a Gleason Score of 3+4 and in 470 (10%) a Gleason Score of 4+3 was present. Median age at RP was 63 years (IQR: 58-68 years), median PSA was 6.4ng/ml (IQR: 4.8-8.7ng/ml) and median prostate volume was 30cc (IQR: 23-40cc). PSA as well as PSA-Density were associated with the quantitative GP 4 fraction above 50% (p-value: <0.001). GP 4 tissue contributed to the pre-operative PSA by 0.37ng/ml per cc, GP 3 and benign prostate tissue combined contributed by 0.062ng/ml per cc (p-value: <0.001). There was no significant difference in PSA contribution between GP 3 and benign tissue. Conclusions: The highest contribution to PSA prior RP originates from GP 4 PCa tumor foci. PSA expression of GP 3 and benign tissue were not significantly different. This confirms the discussed potential indolent nature of GP 3 PCa. Within intermediate risk PCa, PSA is a strong surrogate parameter for the amount of GP 4 PCa tissue. Further confirmatory studies including e.g. imaging data are needed for excluding potential selection bias. SOURCE OF Funding: None.
