Cancer survival rates in England are "disgracefully" low, the charity behind research which revealed a postcode lottery of cancer care across the country said.
"It is a disgrace that our survival rates continue to lag behind other European countries," Juliet Bouverie, director of services and influencing at Macmillan Cancer Support, said, warning that we face falling further behind.
The charity has estimated that if the survival rates of the best-performing areas in England were matched across the country, 6,000 more cancer patients would survive.
They also found areas with the poorest survival rates are on average failing to meet at least one key NHS waiting time target for treatment.
This analysis shows an inexcusable postcode lottery which is responsible for 6,000 people dying needlessly within 12 months of being diagnosed with cancer every year,
It's a no-brainer - when patients have to wait longer for diagnosis and treatment their chances of surviving are significantly reduced.
It is also a disgrace that our survival rates continue to lag behind other European countries. Failure to act now will see us fall further behind.
All the Westminster political parties must make cancer a top health priority ahead of the general election and commit to reducing the number of people who are diagnosed late.
Macmillan Cancer Support has released figures that show four in ten cancer patients die within 12 months in the worst-performing English regions.
In Barking and Dagenham, east London, 38% of patients die within a year of diagnosis.
The same proportion of patients die in this time frame in Crawley, West Sussex, Newham, east London, Swale, Kent, Thanet, also in Kent, and the Vale Royal health area - which covers Winsford, Northwich and surrounding rural areas in Cheshire.
According to Macmillan's analysis of Office for National Statistics data, 37% of people in Medway, Kent, die within 12 months of diagnosis, 36% die within a year in Waltham Forest, north east London, and the same proportion die in this time frame in Telford and Wrekin in the West Midlands and in Luton, Bedfordshire.
A "worrying" number of patients are waiting more than the recommended six weeks for key diagnostics tests that detect cancer and other diseases, according to a charity.
Macmillan Cancer Support has raised concerns about the delays, which it said have reached a six-year high.
Latest NHS England figures show that 16,981 patients were waiting six weeks or more for 15 diagnostic tests including MRI and CT scans, audiology assessments or cardiac echos - or 2.2% of all of the patients waiting for such tests.
In April 2008, just 2,904 patients were waiting for these checks.
The British Medical Association (BMA) has said the profession must "guarantee" that older cancer patients "are treated with care and respect" after claims some are denied treatment solely on their age.
It is important that all healthcare professionals ensure that patients are treated on the basis of their clinical need.
With an increasingly ageing population, it should be a key part of medical professionalism to guarantee that older patients are treated with the care and respect they deserve.
Macmillan Cancer Support said health workers should ensure decisions over cancer treatment take into account a patient's physical and mental health and not be based on age alone.
The National Cancer Intelligence Network (NCIN), which carried out the research into pensioner survival rates alongside the charity, joined the call for wider assessment.
NCIN's clinical lead Dr Mick Peake said: "It is vital that all patients receive the best and most effective treatment based on the nature of their cancer and their fitness for treatment and that chronological age alone is not the deciding factor.
"We know that cancer survival rates in older patients in many other countries are better than in the UK and ensuring optimal treatment at all ages is the way of tackling this issue."
A leading charity has warned cancer patients are being "written off" as being too old for treatment, saying assessments are ignoring fitness levels to judge on age alone.
Macmillan Cancer Support spoke out after finding more than 130,000 pensioners who have been diagnosed with cancer have gone on to live for at least a decade, including 8,000 patents over the age of 80.
The charity's chief executive, Ciaran Devane, said: "With a proper assessment and appropriate treatment, our research shows that many older cancer patients can live for a long time and can even be cured.
"The barriers to getting treatment - which include age discrimination and inadequate assessment methods - must be tackled now so more older people can survive cancer and live for many years."