Off-label use of anticancer drugs in eastern Switzerland: a population-based prospective cohort study.

Purpose: Prevalence data on the off-label use (OLU) of anticancer drugs are limited despite OLU being controversial for medical, pharmaco-economic, and ethical reasons. We therefore quantified and characterized the OLU of anticancer drugs and compared OLU based on the national drug label with international treatment recommendations.

Methods: We prospectively collected data on patients receiving systemic anticancer therapy between October and December 2012 at hospitals affiliated with the Eastern Switzerland Oncology Network. Individual data on patient characteristics, tumor disease, and systemic treatment were collected, and each individual treatment was compared with the national drug label and international treatment guidelines.

Results: A total of 985 consecutive patients receiving 1,737 anticancer drug treatments were included in the study. Overall, 32.4 % of all patients received at least one off-label drug, corresponding to 27.2 % of all anticancer drugs administered. Major reasons for OLU were the lack of approval for the specific disease entity (15.7 %) and modified application of the anticancer drug (10 %). OLU that was unsupported by the current European Society for Medical Oncology (ESMO) treatment recommendations was rare (6.6 %) but higher for bevacizumab (29.6 %) due to its use in treating advanced ovarian cancer beyond the second-line setting and advanced breast cancer beyond the first-line setting and for lenalidomide (22.6 %) due to its use in treating Non-Hodgkin lymphoma.

Conclusions: Based on data collected on our patient cohort, OLU of anticancer drugs in a European clinical setting applies to one-third of all cancer patients. ESMO-unsupported use of chemotherapies or molecularly-targeted drugs is rare, opposing concerns that the off-label use of newer anticancer drugs is a substantial clinical problem.