I've been aware of this piece of legislation for years. I don't know how or why it came to my attention but I was aware that it was illegal to market a cure for cancer. My Journey therapist puts out various pieces of marketing content and I've been helping her with this recently. A couple of times I've had to suggest she removes the word cancer for fear of official retribution.
Today I thought I'd look it up - now that you can look up anything on Wikipedia (what a brilliant resource!) And I'm amazed to see that it's not just that claiming a cure is illegal, there's a clause prohibiting taking any part in publication, except under specified conditions, of advertisements that "offer to treat any person for cancer, or to prescribe any remedy therefor, or to give any advice in connection with the treatment thereof".
There have been one or two tweaks to this legislation the citation says but intrinsically this is it. Obviously the medical professions, pharmaceutical companies, etc., are granted a waiver.
No doubt this is why Chris Woollams at Canceractive.com
has prominent paragraphs on his web site which indicate that it is not providing advice or recommendations. In fact looking at his site it certainly makes an ass of the law. It seems to me that it's about time there was a complete review of the Cancer Act 1939 because things have changed a great deal in the seventy years since it was drafted.