When Deborah James was diagnosed with cancer, the odds were stacked against her. Just 8% of patients with terminal Stage 4 bowel cancer live for five years. And she was only 35 years old. 

But James made it to five years. And in that time she quit her job as a deputy headteacher, started a blog, newspaper column and then a podcastAn audio programme that you can download and listen to. about life with cancer, raised £6.8m for cancer research and was made a dame by Prince William. 

Yesterday, tributes poured in for the cancer campaigner after her family announced her death aged 40. James was "a person of unbelievable tenacity who turned the worst possible situation into an opportunity to inspire and educate," tweeted comedian Mark Watson. 

Even the British prime minister, Boris Johnson, paid tribute: "The research her campaign has funded will be her enduring legacy. Because of her, many many lives will be saved." 

Key to this legacy could be one area of research in particular - personalised medicine. Experts call it "one of the most fundamental breakthroughs in cancer medicine" in recent decades. And it is a cause that James was passionate about. 

In the past, cancer was often treated with a "one-size-fits-all" approach. People with bowel cancer or breast cancer were given the same doses of the same medicines. The treatments available, including chemotherapyA treatment for cancer that uses powerful drugs to kill cells., often have terrible side effects. 

But our understanding of cancer is changing rapidly. Today, scientists can map the genetics of individual tumours. One person's tumour may be very different to someone else's, even if it is in the same part of the body. 

Researchers think the answer is a more precise, personalised approach to medicine. Scientists can choose medicines, such as immunotherapyImmunotherapy works by enhancing the ability of the body's immune system to spot and destroy cancer cells.  drugs, that match the way individual tumours spread. 

Professor Richard Wilson is an expert in cancer medicine at Glasgow University. He hopes that one day, everyone will be able to have their genes mapped to show what their cancer risk might be. They could then receive targeted drugs or even vaccines to prevent illness.

And it is not just cancer treatment that could one day be personalised. Already, the research is being applied to mental health conditions and other bowel diseases. 

But even experts admit that implementing widespread personalised medicine may not be simple. 

One major concern is patient privacyBeing able to keep details about your life to yourself without everyone else knowing. . The UK BiobankA non-profit study investigating how someone's genetics and surroundings contribute to the development of disease. It began in 2006. holds biological samples from half a million people. The data inside could revolutionise medicine. But patients must sign up without knowing how researchers could use their genes in the future, including after death. 

Others wonder about the wisdom of informing people that they have a high likelihood of developing a life-altering disease while they are still well. Finding out that they will one day develop an untreatable illness could actually make a patient's life worse, not better. 

But many are sure: if James's hopes for the future of personalised medicine are realised, millions of lives could be saved around the world. 

Yes: One day, we will consider today's treatments for many common diseases inhumane. Personalised medicine will revolutionise the treatment of cancer and many other serious illnesses.

No: The research is exciting, but sceptics have clear concerns. Medicine based on DNA could infringe on people's privacy. And the expense means that only the richest will be able to afford the results.

Or... For now, the jury is still out. Genetic testing will likely transform how we treat some illnesses, but we cannot yet know what its limits will be. Traditional treatments will still be vital.