The Validity of a New Procedure-Based Definition of Cancer Status in Patients with Breast-, Lung- and Colorectal Cancer in the Danish National Patient Registry

Abstract

Background/Aim

The Danish National Patient Registry (DNPR) provides unique epidemiological insight, but often lacks granular data. We propose a procedure-based definition of cancer status in patients with breast-, lung- and colorectal cancer, which can be applied to administrative health databases. New definitions of cancer status are needed as mortality and morbidity are closely linked to cancer status, yet most studies only use duration since cancer diagnosis as a severity marker. The aim of the study was to validate a new pragmatic definition.

Methods

Medical journals of 600 patients, with breast-, lung- and colorectal cancer from the Department of Oncology at Herlev-Gentofte Hospital were retrospectively reviewed. We defined active cancer as a cancer diagnosis, not followed by a potentially curative procedure within 6 months of the diagnosis. The remaining patients were characterized as having non-active cancer. This dichotomization was then compared to a cancer status assessment based on treatment received and paraclinical test such as their first post-procedural control scan. Based on this comparison, we calculated the positive predictive value (PPV) of our definitions of active and non-active cancer.

Results

The calculated PPVs for active breast-, lung- and colorectal cancer were 87% (CI 95%: 0.74–0.99), 91% (CI 95%: 0.87–0.96) and 82% (CI 95%: 0.73–0.91). The PPVs for non-active breast-, lung- and colorectal cancer were 95% (CI 95%: 0.92–0.99), 91% (CI 95%: 0.82–0.99) and 73% (CI 95%: 0.66–0.81), respectively.

Conclusion

We found an overall high PPV for both active and non-active cancer across all three types of cancer.

Keywords:

• active cancer
• non-active cancer
• DNPR
• validation
• epidemiology

Ethics

The study was approved by the legal department at Herlev-Gentofte Hospital including directors, and Chief physicians at the Departments of Cardiology and Oncology (Ref. 21022478). Ethical approval in retrospective register-based analysis is not required in Denmark.

Acknowledgments

This study was supported by a grant from the Karen Elise Jensen fund (29-4-2021).

Disclosure

Dr Morten Lamberts reports personal fees from Speaker fee, personal fees from Speaker fee, personal fees from Speaker fee, outside the submitted work. The authors report no other conflicts of interest in this work.