Completeness and concordancy of WHO grade assignment for brain and central nervous system tumors in the United States, 2004-2011

Central nervous system (CNS) tumors are categorized and graded for clinical and research purposes according to the World Health Organization (WHO) scheme which segregates tumors by histological type and predicted biological behavior. However, reporting of WHO grade in pathological reports is inconsistent despite its collection in cancer registration. We studied the completeness, concordancy, and yearly trends in the collection of WHO grade for primary CNS tumors between 2004 and 2011. Data from the Surveillance, Epidemiology and End Results program were analyzed for the percentage of histologically diagnosed primary CNS tumor cases with concordantly documented WHO grades between 2004 and 2011. Yearly trends were calculated with annual percentage changes (APC) and 95 % confidence intervals (95 % CI). Completeness and concordancy of the collection of WHO grade varied significantly by histological type and year. The percentage of cases with documented WHO grade increased significantly from 2004 to 2011: 39.0 % of cases in 2004 had documented WHO grade, while 77.5 % of cases had documented grade in 2011 (APC, 10.3; 95 % CI: 9.0, 11.5). Among cases with documented WHO grade, the percentage graded concordantly increased significantly from 89.1 % in 2004 to 93.7 % in 2007 (APC, 1.8; 95 % CI: 1.0, 2.6) and these values varied over time by histological type. One common trend among all histologies was a significant increase in the percentage of cases with documented WHO grade. A sizeable proportion of reported CNS tumors collected by cancer registrars have undocumented WHO grade, while a much smaller proportion are graded discordantly. Data collection on grade has improved in completeness and concordancy over time. Efforts to further improve collection of this variable are essential for clinical care and the epidemiological surveillance of CNS tumors.