Do Standardised Prognostic Algorithms Reflect Local Practice? Application of EORTC Risk Tables for Non-Muscle Invasive (pTa/pT1) Bladder Cancer Recurrence and Progression in a Local Cohort

Abstract

A risk calculator algorithm to allow prediction of probabilities of 1- and 5-year recurrence and progression rates in individuals with pTa/pT1 bladder cancer has been proposed by the European Organisation for Research and Treatment of Cancer (EORTC) and was incorporated into the European Association of Urology guidelines in 2006. We attempted to validate this algorithm in a cohort of patients with known outcome. Prognostic data were collected from a consecutively presenting cohort of 109 patients with non-muscle invasive (pTa/pT1) transitional cell cancer (TCC) at a single institution between 1983 and 1985. Using the same statistical models as in the EORTC original paper, predicted probabilities of 1- and 5-year recurrence and progression were calculated. Patients were divided into four risk groups for recurrence (Ir-IVr) and progression (Ip-IVp), respectively, using six prognostic criteria. These were then compared to the probabilities predicted in the EORTC algorithm. The predicted 1- and 5-year probabilities of recurrence were significantly higher in the study population as compared to the original EORTC algorithm for all four risk groups. The predicted 1-year probabilities for progression in groups Ip/IIIp and at 5-years for groups Ip/IIp were in accordance with the original algorithm, but were higher for the other progression groups. The concordance for the model of prediction using the study group for recurrence at 1 and 5 years was 62 and 63%, respectively, and for progression was 65 and 67, respectively. We were unable to validate the proposed algorithm in our group of patients. Although our study has limitations that prevent firm conclusions on the validity of the algorithm, it does expose some of the drawbacks of standardised nomograms when applied to local clinical practice.