Nearly half of American oncologists have recommended that their patients use medical marijuana, even though less than 30% consider themselves knowledgeable on the topic, according to a new survey by the Dana-Farber Cancer Institute in the Journal of Clinical Oncology.

Why it's happening: Ilana Braun, chief of Dana-Farber's Division of Adult Psychosocial Oncology, thinks that oncologists often find themselves succumbing to an uncomfortable position when their very ill patients request a therapy that's now legal across most of the country — even though its efficacy lacks strong scientific evidence.