The NHS in England has now missed its flagship cancer target for more than 1,000 days with one in four patients facing delays getting treatment.
Hospitals are meant to start treatment within 62 days of a GP referral – and have been set a target of achieving that for 85% of patients.
But latest figures, for January, showed 76.2% were seen on time – the worst performance since records began.
The last time the target was met was in December 2015.
In fact, monthly figures show the target has only been met three times in the past five years.
During that time, 130,000 patients have waited longer than they should for their life-saving treatment.
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‘I feel let down’
One of the patients who has faced delays is Lisa Pannen, 49, who works as an NHS manager.
She waited three months for her bowel cancer treatment to start after long delays waiting for a diagnosis.
She now has advanced bowel cancer that has spread to her ovaries and abdomen. She says she feels “let down”.
“It was extremely frustrating as I felt like I was left floundering for weeks and no one was listening to me.
“I was in intense pain and had a family history of bowel cancer and yet it felt like these things were being ignored.
“I genuinely feel that because of these long referral times all my worry and anxieties were heightened, and it’s made the treatment 10 times harder to deal with,” said Ms Pannen.
Cancer charities said the deterioration in performance was worrying and putting patients at risk.
Sara Hiom, from Cancer Research UK, said: “These figures show an NHS under continued strain, with many patients still waiting too long to get a diagnosis and start treatment.”
Dominic Bell, a manager at Macmillan’s support line, added the delays were causing real distress.
“I’ve worked on the support line for the last seven years and throughout that time, we’ve taken more and more calls from people going out of their mind with worry while they wait for a diagnosis and treatment.
“Dealing with the prospect or the reality of a cancer diagnosis can be one of the most difficult experiences people will go through in their lifetime.”
Other parts of the UK are also struggling.
Scotland, Wales and Northern Ireland all expect 95% of patients to be seen in 62 days.
The last time any of those nations met the target was 2012.
The 62-day goal is one of the few targets the NHS in England is proposing to keep in its shake-up announced earlier this week.
Meanwhile, only 84.2% of patients in February were seen in four hours in A&E departments, which was again a new record low.
This represents a small drop of 0.2 percentage points since January.
A spokesman for the NHS in England acknowledged winter was proving challenging, saying there had been “significant” increases in demand.
“NHS staff across the country have been working incredibly hard,” he added.