Since the early 1950s, a modified form of amygdalin has been promoted under the names laetrile and "Vitamin B₁₇" as a cancer cure. In reality, laetrile is not a vitamin, and studies have found it to be ineffective, dangerously toxic due to its cyanide content, and potentially lethal. The promotion of laetrile to treat cancer has been described in the medical literature as a canonical example of quackery, and as "the slickest, most sophisticated, and certainly the most remunerative [profitable] cancer quack promotion in medical history."