Monitoring potentially modifiable lifestyle factors in cancer survivors: A narrative review on currently available methodologies and innovations for large-scale surveillance

In most European countries, the prevalence of cancer has increased from 1–3% in the 1990's to 4–5% in the 2010's. This increase is largely due to earlier detection and improved treatment. The number of cancer patients who survive longer than 5 years after their primary diagnosis is increasing, emphasizing the need for research in cancer survivors focussing on improving quality of life and cancer prognosis. In this narrative review, we provide an overview of the current and novel methodologies for the ambulant assessment of potentially modifiable lifestyle factors in large-scale prospective studies and discuss future innovations for optimal surveillance of cancer survivors. Lifestyle factors described are potentially modifiable and include dietary intake, body composition, alcohol consumption, smoking behaviour and physical activity. To date, mostly questionnaires are used, but many monitoring tools are already available that allow ambulant measurements. However, technological improvements are still needed to longitudinally measure lifestyle factors on a large scale from diagnosis onwards. Measuring lifestyle factors non-invasively in a home setting could help to increase its feasibility and ultimately improve our understanding of the individual and synergistic effects of lifestyle factors on quality of life and long-term outcomes. In the process of developing such surveillance programmes, several aspects should be taken into account including, but not limited to, methodological considerations, study design optimisation, patient perspectives, privacy issues and information and communications technology solutions to capture, store and analyse big data. Future large-scale lifestyle surveillance studies in cancer survivors will, in addition to questionnaires, increasingly include ambulant monitoring using sensors and wireless tools as this lowers patient burden, provides objective information and facilitates longitudinal data collection.