[shoyer]

It may be "too often" that new treatments are compared to placebos, but it's not the prevailing practice, at least for serious indications like cancer. It would clearly be unethical to deny people proven treatments would extend their lives. To quote cancer.gov (http://www.cancer.gov/cancertopics/factsheet/clinicaltrials/...):

  10. Are placebos used in cancer treatment clinical trials?

  The use of placebos as comparison or “control”
  interventions in cancer treatment trials is rare. If a
  placebo is used by itself, it is because no standard
  treatment exists. In this case, a trial would compare the
  effects of a new treatment with the effects of a placebo.
  More often, however, placebos are given along with a
  standard treatment. For example, a trial might compare the
  effects of a standard treatment plus a new treatment with
  the effects of the same standard treatment plus a placebo.