The use of population-based data is a relatively accessible and cost-effective approach to study long-term outcomes in oncology. Also in older patients with cancer, longer-term outcome studies are limited and population-based data could help address this gap. Under the lead of UZ Leuven and the Belgian Cancer Registry (BCR), a national study was initiated to explore the association between the general health status of older patients with cancer as assessed by geriatric screening and assessment, and long-term outcomes as captured by population-based data. To this extent, data previously gathered within the context of a multicentre clinical study will be linked with three population-based databases: cancer registration data from BCR, healthcare reimbursement data from InterMutualistic Agency and hospital discharge data from Technical Cell. The major advantage of these population-based data is their longitudinal nature, which allows to follow a (sub)population across several years. The downside is their lack of clinical information. One way to partially overcome this limitation is to supplement population-based data with primary study data to investigate more clinically relevant outcomes. Although often scientifically interesting and appealing, coupling with population-based data demands intensive administrative efforts including an authorisation demand at the Information Security Committee. During the whole process, special attention should be given to privacyrelated aspects of the use and linkage of these data to ensure confidentiality.

BELG J MED ONCOL 2021;15(7):362-6)