Nearly one-fifth of all lung cancer sufferers at St George's Hospital may have experienced potentially life-threatening delays in their treatment, a research project has revealed.

About 18 per cent of all patients did not have their x-rays followed up promptly at the hospital in Tooting, south London.

The alarming findings have triggered tighter check-up procedures which could be copied throughout the NHS.

Shockingly, St George's fares better than most other NHS hospitals - with delayed lung scan follow-ups predicted at about 20 to 25 per cent.

The results come hot on the heels of Roehampton lung cancer victim Roy Harward twice being refused chemotherapy treamtent by Wandsworth Primary Care Trust.

St George's NHS Healthcare Trust head of governance Lesley Stuart, who spent three years researching the project, said it was impossible to say how many patients had been affected by the delays.

She said: "One thing we can do is to encourage patients to ask doctors for their results. Do not always assume that no news is good news.

"If you have been sent for an x-ray or scan and did not get anything back, then contact your doctor."

Ms Stuart said, in some cases clinicians had not followed up radiologist reports promptly enough.

She added that all scans revealing a potential cancer are now sent to each departments' cancer specialist co-ordinator, to ensure a prompt follow-up if necessary.

The National Patient Safety Agency (NPSA) could follow up St George's safety procedure nationally. An NPSA spokeswoman said: "We anticipate issuing a safer practice notice to the NHS before the end of the year.

"In addition, the NPSA has raised the issue with other agencies including Connecting for Health and NHS software providers to ensure that, in the longer term, new electronic systems being introduced to the NHS have appropriate audit mechanisms for tracking test results and recording actions taken against them."

Ms Stuart and staff tracked through the x-ray history of 100 patients already being treated for lung cancer before releasing their conclusions.

She said: "What did it for me was the experience of one particular patient, which is when I decided that we needed to determine how often this type of problem occurred. I still keep in touch with the family."