The association of type and number of high-risk criteria with cancer specific mortality in prostate cancer patients treated with radiotherapy

BACKGROUND: To assess the association between of type and number of D'Amico high-risk criteria (DHRCs) with rates of cancer-specific mortality (CSM) in prostate cancer (PCa) patients treated with external beam radiotherapy (RT).

METHODS: In the Surveillance, Epidemiology, and End Results database (2004-2016), we identified 34,908 RT patients with at least one DHRCs, namely prostate-specific antigen (PSA) >20 ng/dL (hrPSA), biopsy Grade Group (hrGG) 4-5, clinical T stage (hrcT) ≥T2c. Multivariable Cox regression models (CRM), as well as competing risks regression (CRR) model, which further adjust for other cause mortality, tested the association between DHRCs and 5-year CSM.

RESULTS: Of 34,908 patients, 14,777 (42%) exclusively harbored hrGG, 5641 (16%) hrPSA, 4390 (13%) had hrcT. Only 8238 (23.7%) harbored any combination of two DHRCs and 1862 (5.3%) had all three DHRCs. Five-year CSM rates ranged from 2.4% to 5.0% when any individual DHRC was present (hrcT, hrPSA, hrGG, in that order), versus 5.2% to 10.5% when two DHRCs were present (hrPSA+hrcT, hrcT+hrGG, hrPSA+hrGG, in that order) versus 14.4% when all three DHRCs were identified. In multivariable CRM hazard ratios relative to hrcT ranged from 1.07 to 1.76 for one DHRC, 2.20 to 3.83 for combinations of two DHRCs, and 5.11 for all three DHRCs. Multivariable CRR yielded to virtually the same results.

CONCLUSIONS: Our study indicates a stimulus-response effect according to the type and number of DHRCs. This indicates potential for risk-stratification within HR PCa patients that could be applied in clinical decision making to increase or reduce treatment intensity.