Vitamin B17, also known as Laetrile and Amygdalin is found in most fruit seeds, namely apricot seeds. The apricot seed was claimed as the cure for all cancers over 35 years ago.
It was even more strongly claimed that when one eats about 7 apricot seeds per day they can never develop cancer, just as one can never get scurvy if they have an orange every day, or pellagra if they have some B vitamins every day.
The pharmaceuticals companies together with the medical establishment pushed the FDA into making it illegal to sell "raw" apricot seeds or vitamin B17 with information about its effects on cancer. Even to this day, you can't get raw apricot seeds in your health food store, only the sun dried ones which have all the important enzymes killed off.
Pharmaceutical companies only conduct studies on patented chemicals they invent so that at the end of their study, if the drug gets approved, they have sole rights on its sale. (They make back tons more than the mere 250 million or so that they invested in drug development.) They never (at least rarely) do studies on foods that can't be patented and that can be sold by any supermarket.