The UK government pledged in May to use artificial intelligence (AI) to prevent more than 20,000 cancer-related deaths a year by 2033, with the prime minister's plans being welcomed by health charities and industry alike. But with the world still reeling from social media data breaches, will the public be open to sharing the most private of information on the scale needed for Theresa May's vision to become a reality? And even if they are, will the information be in any fit state to be shared? On the face of it, the NHS is the perfect place for AI and big data to come together to revolutionise the way diseases are diagnosed and treated. Every day, the health service has access to reams of the 21st century's most precious commodity – data.