A pioneering blood test that can detect more than 50 cancers before symptoms appear could save tens of thousands of lives a year, promising new research suggests.Results of an NHS-backed trial show the Galleri test – dubbed ‘the Holy Grail’ for cancer – helps flag four times as many cancers when added to current screening programmes.In practice this could prevent one in five late-stage diagnoses - a major contributor to the 170,000 cancer deaths a year in the UK.Doctors involved in the trial say the potential impact on survival is enormous, with up to 30,000 lives saved every year.The test, made by American pharmaceutical firm Grail, looks for fragments of cancerous DNA that have broken off a tumour and are circulating in the blood.This ‘signal’ allows doctors to pick up traces of the disease months or even years before symptoms appear, when cancer is at its most treatable.The trial, launched by the NHS in 2021, involved testing more than 142,000 adults aged 50 to 77, with nearly one in 100 getting a positive result over three tests.In 52 per cent of these cases, cancer was later confirmed. The test, analyses blood samples for tiny fragments of cancerous DNAThe trial also saw a 25 per cent fall in the number of cancers first picked up in A&E, when patients are already severely unwell – one of the strongest predictors of poor survival.Doctors said this shift alone could transform outcomes for thousands of patients.Presenting the results ahead of the annual meeting of the American Society of Clinical Oncology (ASCO), Sir Harpal Kumar, Chief Scientific Officer of Global Clinical and Medical Affairs at GRAIL labelled the findings ‘extremely important’.He added: ‘Galleri represents a potential transformational shift in cancer detection, moving us to a more comprehensive and proactive approach where doctors can offer treatment and not just end of life care – that is the difference,’ he said.It is also hoped it will reduce the number of false positives thrown up by current screening programmes, which include those looking for early-stage breast, bowel and cervical cancers.An estimated three million people in the UK are sent for urgent investigations every year because they have symptoms that might be cancer.Just six per cent of these are handed a diagnosis, meaning they may have been subjected to unnecessary invasive testing and worry.Sir Kumar continued: ‘If we had a test that was far more predictive, we would be able to use some of that diagnostic capacity where it would deliver greater benefit. Jan Kitching was diagnosed with stage 2 bowel cancer after her third blood test ‘As treatment options continue to advance, screening frameworks must evolve in parallel.’The trial was criticised earlier this year for failing to meet an endpoint of reducing the number of cases caught at stage three and four - when the disease has already spread to another part of the body.But the newly published results tell a different story.Despite this, today one insider cast doubt on whether the test would every get NHS approval. Speaking to The Telegraph, an unnamed source inside the trial claimed they 'couldn't see any chance' of a national rollout. The trial showed particularly promising results for certain types of cancer. Stage 4 oesophageal cancer diagnoses fell by more than 57 per cent among those offered the test.For bowel cancer, stage 4 diagnoses were reduced by over a third.In England, the survival rate for bowel cancer diagnosed at stage 4 is shockingly low, with just 11 per cent of patients reaching this milestone. But when it’s caught at stage three, 64 per cent of patients have a chance of surviving their cancer for five years.This, doctors say, makes a profound difference.‘We did see a substantial decrease in stage 4 cancers, but this was outweighed by an overall increase in the number of stage 3 cancers picked up,’ Sir Kumar conceded.