Breastcancer.org, one of my favorite sites, has important information on clinical trials for breast cancer:
Clinical trials are research studies in which people agree to try new therapies (under careful supervision) in order to help doctors identify the best treatments with the fewest side effects. These studies help improve the overall standard of care.
Today, fewer than 5% of breast cancer patients receive treatment for their disease in a clinical trial. Why? One factor is that information about current trials and how to enroll in a trial are often not well understood. In this section, you can learn more about what clinical trials involve and how to join one. more.