A quarter of patients diagnosed with cancer in London A&E departments are dead within two months, according to new research.
Experts found that people diagnosed in an emergency tend to have cancer that has spread around the body and also often have cancers that are harder to treat.
The new study, presented at the National Cancer Research Institute (NCRI) cancer conference in Liverpool, analysed data from almost 1,000 patients diagnosed at 12 A&E departments across north east and central London and west Essex during 2013.
Average survival was less than six months for the overall group of patients, with only 36% still alive one year after diagnosis.
Half of all patients under 65 had died by 14 months.
For older patients aged 65 to 75, half had died five months after diagnosis, while only 25% were alive beyond a year.
For those aged over 75, half had died after three months, with only a quarter surviving past one year.
Study author, Professor Kathy Pritchard-Jones, said: "These shocking figures hammer home what we already know to be true: early diagnosis can make a huge difference in your chances of surviving cancer.
"Around a quarter of all cancer cases are being diagnosed following presentation in A&E and the vast majority of these are already at a late stage, when treatment options are limited and survival is poorer.
"And many of the patients diagnosed through A&E have other health conditions that may complicate their treatment."
Harpal Kumar, Cancer Research UK's chief executive, said: "Too many people are still diagnosed in hospital A&E departments and that must change if we're serious about having the best cancer survival in the world.
"We've made good progress during the last seven years. But these figures show much more needs to be done to give patients the best chance of surviving their disease, regardless of their age or where they live."