Many clinical trials have restrictive entry criteria to insure homogeneity of the subject pool which increases power and allows the study to proceed with a not too outrageous sample size. But what if you (or one of your patients) would really benefit from being part of the trial, but does not meet the entry criteria? This study discusses the ethical problems that ensue when a doctor is faced with such a choice.
Pauline W. Chen. Bending the Rules of Clinical Trials. The New York Times, October 29, 2009. Available in html format.