Off-label antineoplastic drugs. An effectiveness and safety study.

Objective: The use of antineoplastic medicines in special situations is common in clinical practice; it is strongly regulated and there is little information on its outcomes. We have analysed such use and health outcomes.

Methods: All off-label cases between 2005 and 2015, with any type of cancer and in any stage were included. Health histories of a single health centre were reviewed to gather information on treatment features, response, survival, andtoxicity.

Results: 85 men and 83 women, aged 56, had largely metastatic tumours treated with a median of 4 cycles (0-118) of chemotherapy, hormone therapy, or biotherapy, for palliative purposes between 1st and 4th lines (80% of cases). The subjective response rate was 32.5%, complete objective 1.9%, partial 8.8%, stabilisation 15.6%, progression 38.8%, and not assessable 35.1%. The median duration of response was 2.5 months (1-17), progression-free survival (PFS) 5 months (4 - 21.3), and overall survival (OS) 11 months (9.2-20.6). In the univariate analysis, performance status, treatment line, number of cycles, and type of response influenced on OS. In the multivariate model, the functional status (HR 0.36; CI 95% 0.17-0.77. P= 0.009) and number of cycles (HR 3.66; CI 95% 2.08-6.44. P= 0.0001) influenced independently on overall survival. The most frequent grade 3 and 4 toxicity were asthenia (19%), neutropenia (10.7%), and nausea and vomiting (8.9%).

Conclusions: Off-label antineoplastic drugs were mostly used in metastatic tumours, with little effectiveness. The functional status must be considered to select the patients to be treated.