Vitamin B 17 is also known as laetrile. It has been used for the treatment of cancer. It has since been banned for use in the United States as it was not found to be helpful against cancer.
One article (1) discussed the treatment of cancer using vitamin B17. It noted that the use of vitamin B 17 in the treatment of cancer patients is controversial. There is little in the research supporting the use of laetrile (vitamin B 17) in cancer patients.
It also noted that the Food Standards Authority or FSA in the United Kingdom has talked about banning the use of vitamin B 17 in treating cancer patients, saying that vitamin B 17 was not a good drug for the use of the treatment of cancer patients. It contains cyanide, which can actually cause cancer and will not treat it.
Source: 1.Alternative Cancer Treatment ‘vitamin’ B-17. http://www.canceractive.com/cancer-active-page-link.aspx?n=512. Accessed 8/29/16.