Up to half of cancer patients in England and Wales are not receiving the correct treatment for their form of the disease, according to a body of senior doctors.
The National Cancer Audit Collaborating Centre (NatCan), which audits care across nine major cancer types, told the BBC prostate, kidney and colon cancers were the worst affected with large variations in care between hospitals.
Among the figures shared with the BBC, NatCan said half of stage four renal cell carcinoma patients, who have seen their type of kidney cancer spread to other parts of the body, do not receive drug treatment.
More than one third (34%) of stage three colon cancer patients do not receive chemotherapy within three months of surgery – a figure which rises above 60% in some hospitals.
And 30% of high-risk prostrate cancer patients do not get surgery or radiotherapy.
NatCan, which is run by the Royal College of Surgeons (RCS) for NHS England and the Welsh government, said the number of patients who are not well enough to be treated or not to receive treatment would not explain the variation between hospitals or number of those missing out.
The body’s clinical director Professor Ajay Aggarwal said reasons for the variations could include staffing and some services deciding older patients could not cope with treatment.
He said: “With cancer, we often hear people talking about what the next breakthrough is but, the fact remains, using what we have better could make a huge difference. It would extend and save lives.”
A Department of Health and Social Care spokesman told the BBC: “Patients should be able to access the cancer care they need regardless of where they live and we are committed to addressing health inequalities as we rebuild the NHS.”
A spokeswoman for the Welsh government said the audit highlighted what areas needed addressing and that it was working with the NHS to “plan, deliver, recover and improve cancer services”.