Figures released by NHS England show that 84.4% of people treated for all forms of cancer from January to March of 2014 began their treatment within 62 days of being urgently referred.
This is 0.6% off the recommended target of 85% and a fall of 1.4% from the period of October to December, 2013, when the figure stood at 85.8%.
The target set by the NHS specifies that 85% of patients should wait a maximum of 62 days to begin their first definitive treatment following an urgent referral for suspected cancer.
According to the latest National Statistics on waiting times for suspected cancer patients accessing NHS services, the 0.6% drop this the first breach of any cancer waiting time since the introduction of the current targets in 2009.
Cancer Research UK has expressed concern that cancer services in England are currently failing some patients.
"The breach of the '62 day target' is very concerning, particularly as 40 per cent of those who aren't treated within two months are having to wait three months or more. This isn't just a missed target – some patients are being failed, " said Sarah Woolnough, Cancer Research UK's executive director of policy and information.
"The target exists to encourage swift diagnosis of cancer and access to treatment, which is vital to improve survival rates. Patients want confidence that suspected cancer is taken seriously and prioritised by the NHS. We hope urgent action will be taken to ensure this breach is a one off."
NHS England data show that over 275,000 people in England are diagnosed with cancer every year and around 130,000 die from the disease. Currently, about 1.8 million people are living with and beyond a cancer diagnosis.
The latest figures also show a drop in the percentage of suspected cancer patients seen by a specialist within two weeks following an urgent referral by their GP, from 95.6% in the October to December 2013, to 95% in January to December 2014. However, this fall of 0.7% from the same period in the previous year does not drop below the NHS target, which stands at 93%.
Andy Burnham MP, Labour's Shadow Health Secretary, said: "David Cameron claimed his NHS re-organisation would improve cancer care. The reality is that he has in fact made it worse.
"Families across England are now facing longer, agonising waits for treatment. Experts are now warning that lives will be put at risk.
"Cancer patients and their families will be waiting to hear an unequivocal pledge from the Prime Minister that he will stop the slide in standards and get cancer services back on track. Nothing less will do."
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The report, "Provider-based Cancer Waiting Times for Q4 2013-14," is available online: www.england.nhs.uk/statistics/ … imes-for-q4-2013-14/