Under-reporting of harm in clinical trials.

Appropriate safety evaluations of anticancer drugs are crucial to assess their benefit-risk ratio. Substantial evidence shows that clinicians under-report harm in clinical trials, and at least three factors contribute to this problem: assessment of harm by clinicians might not represent the experience of patients; harm might be detected within trials, but is not reported appropriately by investigators or reporting is influenced by sponsors; and short-term follow-up might not detect long-term and potentially serious toxicities. Additionally, because of the selection of patients with good functional status in clinical trials, study results might not apply to patients treated in everyday clinical practice. New approaches for the conduct, oversight, and reporting of clinical trials should include patient-reported assessment of side-effects. Effective pharmacovigilance programmes and large-scale observational studies are needed to improve understanding of the tolerability of anticancer drugs in a real world setting.