Bowel cancer patients should begin treatment within four days of diagnosis - or risk cutting their chances of survival by a third, new research suggests. Meanwhile, those who wait more than a month and a half to start a regimen - which usually involves surgery and chemotherapy - are 55 per cent more likely to see their cancer spread, compared to those who are seen immediately.The researchers, from the Indiana University School of Medicine, also found that delays are particularly risky for those who need chemotherapy to shrink tumours prior to surgery. When spotted at early stages, 93 per cent of bowel cancer patients will survive at least five years. This figure drops to 59 per cent if the disease is caught at later stages.In England, NHS patients must begin treatment for cancer within two months of diagnosis, as per Government targets. However the latest figures show this goal is only met for around 70 per cent of patients.The latest data comes amid what's been termed an 'explosion' in bowel cancer cases among young people.More than 2,400 people under 50 are now diagnosed annually in the UK – an increase of around 25 per cent over the past decade. Delays to bowel cancer treatment even of just four days may significantly increase the risk of the disease spreading, a study suggestsMeanwhile, in the US, the disease became the biggest cancer killer of young people earlier this year. Recent studies estimate bowel cancer mortality rates for under-50s in the UK could jump by 39 per cent for women and 26 per cent for men.Bowel cancer – also known as colorectal cancer – is the fourth most common cancer in the UK, with more than 48,000 people diagnosed and 17,700 deaths each year. But like most cancers, it tends to react well when treated early. The latest study aimed to analyse how delays to treatment affected how the cancer spreads – which can drastically reduce survival rates. Metastatic bowel cancer, or stage four disease most commonly means the disease has spread to the liver, lungs or abdomen, and is harder to treat.