A mixed-methods study of methodological approaches in population-based cancer registries in the North and South

Population-based cancer registries (PBCRs) are essential for cancer surveillance; reliable and comparable data depending on both methodological standards and operational organization. While international guidelines define core quality indicators, less is known about how governance structures and registry workflows influence data quality across different healthcare settings.

We conducted a convergent mixed-methods study involving seven PBCRs: six in Colombia and one in Haute-Vienne, France. Breast cancer was used as a model disease. Quantitative analyses evaluated comparability and validity indicators over 2009-2017, including variable completeness, microscopic verification, death-certificate-only cases (DCO), and coding practices. Semi-structured interviews with 16 registry professionals explored governance, data sources, coding procedures, quality control, workforce organization, and operational challenges. Findings were integrated using a joint display approach.

Overall, 25,073 breast cancer cases were analyzed. Core incidence variables, including sex, age, diagnosis date, tumor topography, and morphology, were nearly complete across registries. Microscopic verification exceeded 90% in all registries, and DCO proportions remained below 2%. In contrast, TNM staging completeness varied substantially. Interviews revealed that this variability was mainly related to institutional integration, access to clinical records, quality-control procedures, staff organization, and legal frameworks governing data access. All registries used ICD-O-3 coding systems, suggesting that organizational factors influenced data quality beyond classification standards alone.

PBCR data quality differences were primarily associated with governance and operational factors. Integrating quantitative quality indicators with qualitative assessment of registry organization may guide improvements in institutional integration, clinical data access, workforce capacity, and sustainable governance.