Oncological outcomes in an Australian cohort according to the new prostate cancer grading groupings

Abstract

BACKGROUND: A new 5-tiered grading grouping system has recently been endorsed for reporting of prostate cancer (PCa) grade to better reflect escalating risk of progression and cancer death. While several validations of the new grade groupings have been undertaken, most have involved centralised pathological review by specialist urological pathologists. METHODS: Participants included 4268 men with non-metastatic PCa diagnosed between 2006 and 2013 from the multi-institutional South Australia Prostate Cancer Clinical Outcomes Collaborative registry. PCa-specific survival and biochemical recurrence-free survival were compared across the five grade groups using multivariable competing risk regression. RESULTS: For the entire cohort, risk of PCa death increased with increasing grade groups (at biopsy) Adjusted subdistribution-hazard ratios [sHR] and 95% confidence intervals [95%CI] were: 2.2 (1.5-3.6); 2.5 (1.6-4.2); 4.1 (2.6-6.7) and 8.7 (4.5-14.0) for grade groups II (pattern 3 + 4), III (pattern 4 + 3), IV (total score 8) and V (total score 9-10) respectively, relative to grade group I (total score < =6). Clear gradients in risk of PCa death were observed for radical prostatectomy (RP), but were less clear for those who had radiotherapy (RT) with curative intent and those who were managed conservatively. Likewise, risk of biochemical recurrence increased across grade groups, with a strong and clear gradient for men undergoing RP [sHR (95%CI): 2.0 (1.4-2.8); 3.8 (2.9-5.9); 5.3 (3.5-8.0); 11.2 (6.5-19.2) for grade groups II, III, IV and V respectively, relative to grade group I], and a less clear gradient for men undergoing RT. CONCLUSION: In general, the new five-tiered grade groupings distinguished PCa survival and recurrence outcomes for men with PCa. The absence of a clear gradient for RT may be due to heterogeneity in this patient group.