How are cancer research studies structured? Cancer research studies are divided into several categories. Before clinical trials in humans are conducted, companies complete research, laboratory testing and animal studies. The human trials use four distinct phases, each one designed to answer specific questions.
Phase 1 trials are the first to involve people as participants. Treatments usually involve a gradual increase in dosing of a drug or drug combination while watching for negative side effects and determining which dosage is best at destroying cancer cells. Participation is limited to a small number of people and is generally reserved for those who do not have good alternative treatment options left to them.
Phase II trials continue to test the safety of a particular drug and begin to evaluate the drugs effectiveness against a specific type of cancer. Anywhere from 25 to100 patients are treated with the same dosage and method of treatment determined to be most successful in the Phase I study. Depending on the goals of the trial, researchers look for evidence that the cancer has been affected in various ways, For example, the tumor is shrinking, has disappeared, or there is an increase in time before a cancer returns. Side effects continue to be monitored for change in severity. At the conclusion of the trial, if enough patients respond to the treatment, it is considered sufficiently effective to proceed to the Phase III level.
Phase III trials compare the safety and effectiveness of a new drug or combination of drugs against the current standard treatment. These studies often enroll a large number of patients in many locations across the country. In order to avoid biases, participating patients are often chosen at random, where a certain percentage receives the new treatment and the others receive the standard treatment. In many cases, neither the patient nor the doctor knows which treatment is being administered until the study is complete. As with all other phases, patients are closely monitored for side effects and treatment is stopped if they are too severe. Based on the results of the clinical trial, if a treatment is shown to be more effective and/or safer than the current standard treatment, it is submitted for approval to the FDA. If approved, the treatment often becomes the new standard of care.
Phase IV trials are conducted after FDA approval of the drug in order to refine treatment and reduce or improve the management of side effects. Even after extensive testing, additional questions can be answered that are not critical for getting the medicine to market, but could further increase the effectiveness of a particular treatment. Researchers further pursue questions such as the optimal length of time for the treatment to be administered and how often the treatment can be administered thereby fine-tuning dosage levels.
Where are clinical trials conducted? Trials can be conducted at large cancer institutions such as the National Cancer Institute, university hospitals, community cancer centers, or physician's offices. Depending on the type of trial, a small number of participants could be treated at a highly specialized facility or hundreds of patients could be involved in studies at cancer centers all over the country.
