Patients selected for these trials are almost always in cancer research centers and have already received all
  known effective anticancer therapy. After the proposed treatment is explained to them, they may volunteer
  to receive the new treatment. There is, therefore, no moral objection to giving this new treatment. Since there
  is "nothing to lose," it is hoped that a specific new agent may in fact prove effective.
      This phase is completed when no unusual problems or toxic effects have been found and the dose
  necessary to produce a biologic effect has been determined. The study can then move to the next phase.
• Phase II  Ten to 20 patients are treated, each with various types of tumors known to be responsive to
  chemotherapy . These might include lymphomas, breast cancer or colon cancer. Since these tumor types are
  known to be responsive, the patients will be those who have already received all standard forms of therapy
  that seem reasonable. The use of a Phase II trial does not deprive anyone of any therapy known to be
  effective. If a significant number of patients with each type of tumor respond to the therapy, the trial moves
  to the next level.
• Phase III  In this phase the new therapy is compared with standard treatment to see if there is an
  improvement in the response or if the same response rate is achieved but with less-toxic side effects.
      A therapy tested in a clinical trial does not necessarily involve a drug not already in clinical use. A new
  treatment often consists of standard drugs used in a new combination or a new sequence, in new dosages or
  even simply given in a new way. But if a new drug is involved and the Phase III trial is successful, the
  National Cancer Institute will approve the drug for general use. Eventually, the new therapy might become
  the standard therapy.