Amazon has been criticised for showing documentaries promoting cancer quackery and unproven cures on its Prime Video service.
Experts accused the company of having 'no idea' what's on its site and added dodgy documentaries could take advantage of vulnerable patients.
There are around 15million Prime subscribers in the UK with access to a library of films and TV shows, some of which may contain 'dangerous' information, experts warn.
Documentary films Second Opinion (pictured), Cancer Can Be Killed and Burzynski: Cancer Cure Cover Up, are all accused of promoting unproven cancer therapies which experts warn could be dangerous to 'vulnerable' patients
An investigation by Wired magazine found the first search result when someone searched 'cancer' was a film called Cancer Can Be Killed.
The documentary claims a woman was 'cured' of cancer in just 30 days after having an alternative treatment in Germany called laetrile.
Laetrile, also known as amygdalin or vitamin B17 – although it isn't a vitamin – turns into cyanide in the body and is touted as a cancer cure.
But scientific research has found there is no evidence to recommend laetrile as a cancer treatment because the risks of taking it outweigh the benefits.
The US's Food and Drug Administration (FDA) and the European Commission banned the drug because it was ineffective and could cause cyanide poisoning, but it can still be bought online.
Laetrile was also the subject of another documentary, Second Opinion, which Amazon recommended to people who watched Cancer Can Be Killed.
Cancer Research UK's head information nurse said promoting unproven or unapproved cancer 'treatments' was a danger to people's health.
'They can interfere with any ongoing treatment in some unknown way, making it less effective or causing patients harm,' Martin Ledwick told Wired.
'Plus they can be extremely expensive, leaving patients and their families in a difficult financial situation.
'Many cancer patients will understandably cling to any hope that is offered to them, however unrealistic.
'As a general rule, if something sounds too good to be true, it probably is.'
In a review beneath one of the documentaries, Second Opinion, a man claiming to be a former cancer patient said he would 'definitely' take an experimental and banned therapy if he got the disease again. Second Opinion is no longer available to watch through a Prime subscription
Google has been accused of promoting an unproven cancer cure which can burn through people's skin.
Adverts for black salve, an