Cancer treatments in stage 3 trials successful up to half of the time About one-fourth to one-half of new cancer treatments that reach assessment in phase 3 randomized clinical trials are eventually proven successful, according to a written report in the March 24 problem of Archives of Internal Medicine. Cancer remains the next leading cause of death in the usa, but constant improvements have been manufactured in survival and other outcomes, according to history information in the article . Not surprisingly investment, little is known about the proportion of scientific trials that have resulted in the discovery of effective new treatments.D., Ph.D., of the H.