The world's largest database of cancer patients is being set up in England in an attempt to revolutionise care, Public Health England has announced.
It will collate all the available data on each of the 350,000 new tumours detected in the country each year.
The aim is to use the register to help usher in an era of "personalised medicine" that will see treatments matched to the exact type of cancer a patient has.
Experts said it was "great news".
The old definitions of cancer - breast, prostate, lung - are crumbling.
Cancer starts with a mutation that turns a normal cell into one that divides uncontrollably and becomes a tumour. However, huge numbers of mutations can result in cancer and different mutations need different treatments.
Research into the genetics of breast cancer means it is now thought of as at least 10 completely separate diseases, each with a different life expectancy and needing a different treatment.
The national register will use data from patients at every acute NHS trust as well 11 million historical records.
It will eventually track how each sub-type of cancer responds to treatment, which will inform treatment for future patients. 'Fundamental change'
Jem Rashbass, national director of disease registration at Public Health England, said: "Cancer-registry modernisation in England is about to deliver the most comprehensive, detailed and rich clinical dataset on cancer patients anywhere in the world."
He told the BBC: "This will fundamentally change the way we diagnose and treat cancer.
"In five years we'll be sequencing cancers and using therapies targeted to it."
The service will also exchange information with Wales, Scotland and Northern Ireland, which have their own registers.
The Department of Health has already committed £100m to sequence the entire genetic code of 100,000 patients with cancer and rare diseases in order to accelerate progress in personalised medicine.
Emma Greenwood, Cancer Research UK's head of policy development, said: "It's great news that this national database has been set up.
"It means we have all the UK's cancer information in one place, making us well equipped to provide the highest quality care for every cancer patient.
"It'll be easier and quicker to further cancer research, and will speed up work to deliver personalised cancer medicine to patients in the future."