P11.28.A Cancer registration and adherence to the WHO 2016 classification of pathology reports for astrocytic tumors in Belgium from 2017 to 2019

Abstract Background The objective of this study is to cross-check the ICD-O-3 topography and morphology codes of registered glioma patients with findings in their pathology reports and to investigate the integration of relevant molecular markers in the final histopathological diagnosis. Materials and methods Since information regarding molecular tests and corresponding conclusions are not available as structured data at the Belgian population level a manual screening of all pseudonymized full text pathology reports available at the Belgian Cancer Registry (BCR) for adult glioma patients diagnosed between 2017 and 2019 was conducted. ICD-O-3 morphology and topography codes from the BCR database (provided by the hospital oncological care programs and laboratories for histopathology), were cross-checked with the data from the pathology reports. Relevant molecular markers were manually extracted from the pathology reports of confirmed glial tumors. The final diagnosis as mentioned in the reports and the integration of the appropriate molecular markers were checked against the WHO 2016 classification. Results For 1.892 of 2.379 registered gliomas (73%), a specific topographic code was provided. For 8% of patients registered with code C71.9 (unspecified region of the brain), a change to a specific topography code was implemented based on details in the pathology reports. For only 98 of 2.186 patients (4,5%) with available pathology reports, the ICD-O-3 morphology code was adjusted based on the information in the pathology reports. For 59 patients this was a change of grade within the same tumor group. In the subgroup of patients with astrocytic tumors, for 314 of 1.887 patients (16,6%) the IDH status (IDH1-IHC or IDH1/2-NGS) was not identifiable in the available reports. For only 1.091 of 1.887 patients (57,8%) the reports provided an integrated diagnosis including molecular findings, while for the other reports the tumor was not specified (NOS) in the conclusion. For 1.309 of 1.887 patients (69,4%), the final diagnosis in the pathology reports was compatible with the molecular markers. For 553 (29%) patients this was not the case because the relevant molecular markers were not integrated in the conclusion although available (i.e. in the conclusion of these pathology reports the tumor was NOS, but details of the molecular test result were however available somewhere in the reports). Conclusion Morphology codes of registered glioma are largely in line with findings in the pathology reports. The use of specific ICD-O-3 topography codes should be further encouraged and also molecular testing and the use of the integrated diagnosis in the pathology reports can be improved. These findings will be further processed and incorporated in the ongoing Quality Indicator project for glioma in Belgium and will be used to develop strategies to further optimize the reporting of these tumors towards the BCR.