The NHS cancer plan was launched in England in 2000
Patients from deprived areas in England are more likely to have a late cancer diagnosis and be admitted to hospital as an emergency, a study suggests.
Women and older people also fare worse in getting a prompt diagnosis, the team from University College London found.
This did not improve despite an extra £570m being invested via the NHS Cancer plan during the first three years of the 2000-2006 study, the study showed.
The government has said cutting cancer inequalities remains a major goal.
Figures for the three most common cancers - colorectal, breast, and lung cancer - were examined for the six-year period.
They showed 564,821 patients aged 50 and over were admitted to an NHS hospital in England with a diagnosis.
Almost a third of patients with colorectal cancer were admitted as emergencies - a proportion which did not improve over time.
More than half of patients with lung cancer were also admitted as emergencies, a figure which got worse over time.
But there was a downward trend in the proportion of patients with breast cancer admitted as emergencies.
In all, patients from deprived areas, older people and women were more likely to be admitted as emergencies.
Patients from deprived areas were also less likely to undergo key procedures for rectal, breast and lung cancer.
There has been much debate over the impact of the NHS Cancer Plan, which was underpinned by an extra £570m in the first three years.
Study leader Professor Rosalind Raine said the Cancer Plan had led to improvements in survival and waiting times but there was a significant group of people who missed out on the benefits of that because their cancer was not picked up early enough.
"The levels of emergency admissions are very high, these are very striking figures and it's not improving over time.
"It's tragic that it's older people and more disadvantaged people and women who are missing out on this gold standard care and we really need to look at what is going on here."
Prof Raine welcomed recent moves by the government to improve early diagnosis but said there were still questions to be answered on why certain groups were more vulnerable to missing out.
A Department of Health spokesman said reducing inequalities in cancer services and outcomes is a major goal of the Cancer Reform Strategy introduced in 2007 and the National Cancer Equality Initiative was set up to tackle this issue.
"During 2009 the major focus of the Initiative was to understand the different factors contributing to inequalities.
"From this work, we are developing plans and will be publishing a practical guide to reducing cancer inequalities early in 2010."
Sarah Woolnough, head of policy at Cancer Research UK, said the study highlights a continuing problem, and one that must continue to be prioritised.
"We know that in this country, cancer is often diagnosed late when it is at an advanced stage, and this is a particular problem among deprived groups.
"This can have a knock on effect on the type of treatment that can be given, and ultimately, on cancer survival."