[Early interruption of a clinical trial: rationale and interpretation]

Early interruption of a clinical trial is not a rare case, and it may be due to several reasons that are summarized in the present article. It is important for the clinician, the primary user of the information derived from clinical trials, to be able to assess whether the eventual interruption of the trial had been planned in the study protocol, whether the study organization was such as to correctly monitor the accrual of efficacy and safety data, who took the decision to interrupt the trial, whether the study patients have been exposed to excessive risks and, finally, whether the conclusions of the study report are valid. In most cases, these issues are carefully assessed during the review process of the study publication (and, of course, by the regulatory authorities) but, particularly for the studies interrupted for "overwhelming evidence of benefit", wisdom and prudence are mandatory, and the results must be considered within the context of all available evidence.