Résumé : Introduction: The introduction of early cancer detection and the improvement in treatment efficacy have led to a significant increase in the survival and the prevalence of (ex) cancer patients. Approximately 40 % of new cancer cases are diagnosed every year in the working age population (20-64 years). Maintaining their quality of life results, among others, in their retain on the labour market. Even though it is necessary to realize the scale of the phenomenon and to plan interventions, no measure allows assessing the rate of return to work among of (ex) cancer patients in Belgium nowadays. Methods: We observe during a five-year period the socio-professional status (inability, disability, unemployment or death) of 645 workers identified in the permanent sample (EPS), having had an oncological multidisciplinary consultation (MOC) in 2011. Results: By the end of follow-up, 24 % of the workers were deceased. Among those who survived 26 % are unable to work, 12 % are unemployed and 63 % do not receive any social benefit. Women and young workers (20-44 years) seemed to have encountered difficulties the most. Conclusions: The results of this study allow giving a prudent first estimation of the return to work of socially insured Belgian citizens of almost 40 %, five years after the first MOC. Nevertheless, the structure of the EPS presents many limitations to the interpretation and reliability of results. We suggest some modifications of the EPS that might offer scientists better opportunities to improve the performance and reliability of such cohort studies.