Independent Validation of the American Joint Committee on Cancer 8th Edition Prostate Cancer Staging Classification

We sought to independently validate the American Joint Committee on Cancer (AJCC) 8(th) edition prostate cancer (PCa) staging classification, which includes the elimination of pT2 subcategories and the reclassification of patients with PSA≥20ng/ml and Gleason Grade Group (GG)-5 as Stage Group III-A and III-C, respectively.

Men who underwent radical prostatectomy at Mayo Clinic between 1987-2011 (n=13,839) were identified from our institutional registry. Outcomes included biochemical recurrence (BCR)-free (bRFS), metastasis-free (MFS), and cancer-specific survival (CSS). Kaplan-Meier analyses and Cox regression models with c-indexes were used.

Median follow-up was 10.5 years (IQR 7.1,15.3). Among patients with pT2 PCa, subclassification demonstrated limited discrimination for bRFS (c-index=0.531), MFS (c-index=0.545), or CSS (c-index=0.525). At the same time, patients with 7(th) edition Stage Group II PCa and PSA≥20ng/ml had significantly worse 15-year bRFS (42.2% versus 58.8%;p<0.001), MFS (78.2% versus 88.8%;p<0.001), and CSS (88.0% versus 94.4%;p<0.001) than patients with 7(th) edition Stage Group II PCa and PSA <20ng/ml, but significantly better 15-year bRFS (42.2% versus 31.3%;p=0.007), MFS (78.2% versus 68.0%;p<0.001), and CSS (88.0% versus 83.4%;p=0.01) than 7(th) edition Stage Group III patients. Meanwhile, patients with 7th edition Stage Group II PCa and GG-5 had significantly worse 15-year bRFS (37.1% versus 57.9%;p<0.001), MFS (63.8% versus 88.5%;p<0.001), and CSS (73.0% versus 94.3%;p<0.001) than patients with 7th edition Stage Group II PCa and GG-1-4, as well as worse 15-year CSS (73.0% versus 83.4%;p=0.005) than patients with 7(th) edition Stage Group III PCa.

Our data support the changes in the new AJCC classification.

The Journal of urology. 2017 Jun 29 [Epub ahead of print]

Bimal Bhindi, R Jeffrey Karnes, Laureano J Rangel, Ross J Mason, Matthew T Gettman, Igor Frank, Matthew K Tollefson, Daniel W Lin, R Houston Thompson, Stephen A Boorjian

Department of Urology, Mayo Clinic, Rochester, MN, USA., Department of Biostatistics, Mayo Clinic, Rochester, MN, USA., Department of Urology, University of Washington, Seattle, WA, USA., Department of Urology, Mayo Clinic, Rochester, MN, USA. Electronic address: .

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