The value of a health insurance database to conduct pharmacoepidemiological studies in oncology.

Some concerns have emerged about the evidence of benefits on survival outcomes or quality of life of new anticancer drugs. In parallel, the decreased cancer mortality leads to an increased number of patients exposed to cancer treatment-related consequences. In this context, pharmacoepidemiology is crucial to assess anticancer drug use, effectiveness and safety in real life conditions. We aimed to describe strengths, limitations and considerations associated with the use of the French national health insurance database (système national des données de santé [SNDS]) to conduct pharmacoepidemiological studies in oncology. The SNDS represents a powerful tool in pharmacoepidemiology owing to its extensive coverage, accurate description and quantification of drug exposure and individual data on patients. The main limitations of this database ensue from the administrative nature resulting in technical difficulties in its management and gaps in availability of data. Another limitation is the lack of accurate identification of diseases, comorbidities or outcomes and potential confounding with notably the lack of data regarding cancer stage, prognosis or risk factors. Finally, the accurate identification of the nature of chemotherapy received by patients is sometimes complex. To minimize these limitations, several approaches and statistical methods could be used as highlighted by national or international initiatives. First, the SNDS may be linked with cancer registry or clinical data. Then, several data sources could be combined using meta-analytical methods. The development of methodological tools and the use of standardized methods are crucial to enhance the quality of studies that can impact clinical practice and guide public decision. Pharmacoepidemiological approaches and pharmacovigilance represent an important cornerstone in oncology for signal detection or long-term follow up of cancer patients. In this context, validated methods to identify cancer patients and to describe chemotherapy regimens within these data should be promoted and remain too scarce despite international guidelines. Moreover, limits and strength of each data sources should be systematically discussed according to the research question. Optimized and framed use of claims database represents a future challenge in onco-pharmacoepidemiology.