This has to be some scam, like 99.9% of "blockchain technology". Why would a data structure has anything to do with cancer? What difference it makes to the sick how is their data stored - on blockchain or in regular database? It's such a negligible detail that it's not going to affect absolutely anything. These blockchain scammers are just preying on suckers who think that if they will invest in something with cutting-edge buzzwords in it, they will become rich in an instant.