Accuracy of kidney cancer diagnosis and histological subtype within Canadian cancer registry data
Introduction: Provincial/territorial cancer registries (PTCRs) are the mainstay for Canadian population-based cancer statistics. Each jurisdiction captures this data in a population-based registry, including the Nova Scotia Cancer Registry (NSCR). The goal of this study was to describe data from the NSCR regarding renal cell carcinoma (RCC) pathology subtype and method of diagnosis and compare it to the actual pathology reports to determine the accuracy of diagnosis and histological subtype assignment.
Methods: This retrospective analysis included patients diagnosed with RCC in the NSCR from 2006‒2010 with an ICD-O-3 code C64.9 seen or treated in the largest NS health district. From the NSCR, method of diagnosis and pathological diagnosis was recorded. All diagnoses of non-clear-cell RCC (nonccRCC) from NSCR were compared to the actual pathology report for descriptive comparison and reasons for discordance.
Results: 723 patients make up the study cohort. 81.3% of patients were diagnosed by nephrectomy, 11.1% radiography, 6.9 % biopsy, and 0.7% autopsy. By NSCR data, 52.8% had clear-cell (ccRCC), 20.5% RCC not otherwise specified (NOS), 12.7% papillary, 4% chromophobe, and the rest had other nonccRCC subtypes. By pathology reports, 69.5% had clear-cell, 15% papillary, 5% chromophobe, only 2.7% RCC NOS. There was a discordance rate of 15.4% between NSCR data and diagnosis from pathology report. Reasons for discordance were not enough information by the pathologist in 45.5%, misinterpretation of report by data coder in 22.2%, and true coding error in 32.3%.
Conclusions: When using PTCR for RCC incidence data, it is important to understand how the diagnosis is made, as not all are based on pathological confirmation; in this cohort 11% were based on radiology. One must also be aware that clear-cell and non-clearcell subtypes may differ between the PTCR data and pathology reports. In this study, ccRCC made up 52.8% of the registry diagnoses, but increased to 69.6% on pathology report review. Use of synoptic reporting and ongoing education may improve accuracy of registry data.
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