# The validity of the information on date of diagnosis of intracranial tumors in the Swedish cancer register

## TL;DR

This study checks how accurate the diagnosis dates of brain tumors are in a Swedish cancer register.

## Contribution

The study validates the accuracy of diagnosis dates for intracranial tumors in the Swedish Cancer Register using radiology data.

## Key findings

- 98.8% of brain tumor patients had diagnosis dates within one month of the register's records.
- Only 1.0% of patients had tumors reported one month to one year after radiological diagnosis.
- 1.2% of patients had tumors reported more than one year after radiological diagnosis.

## Abstract

Purpose: To assess the validity of information on the date of diagnosis of intracranial tumors in the Swedish National Cancer Register. Materials and Methods: The study was conducted in Region Stockholm, covering approximately 2.4 million inhabitants. Data from the Image and Function Service (BFT) archive, which contains a population-based database of all diagnostic radiology in the Stockholm Region, was used. The study included all primary cases of intracranial tumors (ICD10 codes C70 and C71) reported from Stockholm to the National Cancer Register from 2010 to 2020. Radiology reports from CT and MRI exams performed from 2000 to 2020 were reviewed. Reports from exams conducted more than one month before the Swedish Cancer Register diagnosis were manually examined to validate the date of diagnosis. Results: For 98.8% of the brain tumor patients and 96.2% of the meningioma patients, the date of first radiological diagnosis was one month or less prior to date of diagnosis in the Swedish Cancer Register. Of the patients with radiological diagnoses more than one month prior to cancer register diagnosis, 30 patients (1.0%) had tumors reported to the register one month to one year after radiological diagnosis, and 36 patients (1.2%) had tumors reported more than one year later. Conclusion: The study found that for patients from the Stockholm Region with intracranial tumors reported to the Swedish Cancer Register during the period 2010 through 2020, date of diagnosis is highly accurate.