DEAR DR. ROACH: Your recent column about the advancement of medical science relying on clinical trials, not testimonials, begs me to ask the following: How are the candidates for these research trials selected? What information is provided to them to consider before volunteering? Are the candidates aware that they may receive a placebo rather than the treatment being tested? Then, upon completion of the trial, are they notified of the results, and finally, are they told whether or not they were part of the control group?

• T.F.

ANSWER: All subjects in trials are protected by a large number of regulations to prevent abuse. The first step is informed consent. The subjects in a trial need to understand the potential benefits and harms of being in a study. The informed consent process (and its documentation) is sometimes quite extensive, particularly in a trial where there is a significant risk, such as a new cancer treatment.

The risks of this treatment need to be carefully explained, and subjects know that they could be assigned to an active treatment or a placebo if it is this type of trial. Some trials compare a new treatment to a standard treatment. A placebo arm is unethical when there is a known, effective treatment.

It is also a standard of research ethics (codified in the Helsinki Declaration) that the results of a trial should be shared with the participants once the trial is complete and published. This usually means knowing which treatment the individual received. If subjects in a trial cannot learn which arm they were in, the investigator needs to provide justification for it.

It is not always the case that a person who was in a trial will be offered the active treatment if it was found to be superior to the placebo they received. Sometimes, despite being effective, the treatment may not be approved for this condition, so it cannot be prescribed. However, if the treatment was found to be effective and approved for the condition, then the person should be offered this effective treatment.

This was one critical error in the Tuskegee Syphilis Study, where subjects were not offered effective treatment (penicillin) for years after it was clear that an effective treatment was available. They did not receive informed consent and were prevented from getting effective treatments outside of the study. The Tuskegee Syphilis Study was such an ethical disgrace that researchers are required to study it to try to prevent similar disasters.