This will continue to happen so long as two things continue to exist:
1) diseases and conditions refractory to treatment or cure by modern medicine
2) expenses related to medical care being born by Americans at a personal level
If you look at other countries, there are absolutely people in positions of power who still push quack medicine because of 1), but 2) creates an extra incentive for desperate or overeager people to try quack medicine.
? expenses related to medical care are borne by americans at a personal level
(2) needs to be nuanced, since we're talking about cancer. Medicare has very good coverage. And EU cancer care can have high out-of-pocket costs. 80% of young European cancer patients report financial difficulties as a result.