Only 40 percent of Americans have a positive overall impression of clinical trials, according to a national survey conducted for Memorial Sloan Kettering Cancer Center.

The survey, which polled over 2,100 people including nearly 600 physicians, found that 28 percent of doctors considered clinical trials as treatments of last resort.

One-third, or 32 percent, of doctors polled said they discuss the topic with their patients at the beginning of treatment—however, 56 percent said they consider clinical trials late in treatment.