# The accuracy and characteristics of gastric cancer treatment information in the national data of the hospital-based cancer registry

## TL;DR

This study evaluates the accuracy of gastric cancer treatment data in a national hospital-based cancer registry, finding that surgical treatments are recorded more reliably than chemotherapy and radiation therapy.

## Contribution

The study provides a detailed analysis of treatment data quality in a national cancer registry, highlighting stage- and treatment-specific variations in data accuracy.

## Key findings

- Sensitivity for surgical treatments decreases in advanced stages, while it increases for chemotherapy and radiation therapy.
- Specificity for all treatments and stages is consistently high, exceeding 90%.
- Coverage rates for all treatments increase with longer time from diagnosis to treatment.

## Abstract

The hospital-based cancer registry is used extensively for research to support cancer control activities by providing an overview of how cancer treatments are provided nationwide. This study aimed to shed light on the quality and characteristics of treatment data in the hospital-based cancer registry using the linked dataset on gastric cancer.

Using the nationally linked data of the hospital-based cancer registry and the health services utilization data, the treatment data in the hospital-based cancer registry for patients who were newly diagnosed with gastric cancer in 2016 and 2017 and received the first course of treatment at their own institutions were examined. The agreement rates between registry data and utilization data were analyzed by stage, treatment, age, period from the date of diagnosis to the date of treatment and hospital type.

The sensitivity of open surgery, laparoscopic surgery and endoscopic treatment tended to decrease in advanced stages, whereas the sensitivity of chemotherapy and radiation therapy increased. Specificity was high for all treatments and stages, at ˃90%. Sensitivity by age was slightly different for chemotherapy and radiation therapy, but specificities did not differ.

For all treatments, the longer the time from diagnosis to treatment implementation, the higher the coverage rate.

The hospital-based cancer registry recorded the treatment performed appropriately. It is necessary to interpret the data from the hospital-based cancer registry whilst keeping in mind that, chemotherapy and radiation therapy are registered less frequently than surgical treatments administered.

Hospital-based cancer registry appropriately recorded the treatment according to the registration rules. The rules of registration period also appeared practical.