One of my previous employers had an amazing story.
His father in law worked as a dentist in his younger years which was around the 1930s/1940s. He spent a lot of things time in the Northern part of Australia so he treated a number of aboriginies. He learnt of a very effective cancer cure from them, particularly oral cancer of which he personally saw at least one aboriginies being totally cured.
He learnt that the cures were a result of eating a plant called Scaevola. This plant grows in the wild.
He spent much of his years trying to bring this cure to the attention of scientists and the Government. He was able to get one research university to undertake some research on it which was very positive. The project was abruptly shut down for unspecified reasons. However, the university had been supplying a number of cancer patients with a liquid form of the plant which they drank every day. These patients insisted that it helped them and the University promised to supply these patients with this medicine until they died.
The Government declared Scaevola as a poison and made it illegal to collect the plant from the wild, stating it as a protected species. However the University was given special clearance to keep providing it to their patients on their list.
I saw my boss go and collect this black liquid for his mother in law once a month. She had been diagnosed with cancer some years prior. She had drunk this medicine for over twenty years without her cancer returning. She died in her early 90s, her husband died a few months later.
My employer showed me the plant, he would collect it from the wild and prepare the medicine on his stove and supply close friends with it who were cancer victims. He was convinced of its healing properties as he had heard of it he many stories his father in law knew of.
They were convinced that the closure of any research into this plant was due to there not being any real interest in such a cheap and simple cure.