More than 40 per cent of people in Herts Valley fail to take up their free bowel cancer screening.
Anyone aged 60-74 and who is registered with a GP will receive a test in the post every two years.
But only 59.4 per cent of people locally take the test – one of the lowest uptake rates in the region.
In the neighbouring area served by North and East Hertfordshire Commissioining Group the rate of uptake was only slightly better, at 61.5 per cent.
Deborah Alsina MBE, chief executive of the charity Bowel Cancer UK, said: “It’s quite simple, bowel cancer screening saves lives.
“I would encourage everyone who’s over 60 to take the test, and for those who are younger to encourage their loved ones over 60 to complete it.
“It could save yours or your loved ones life.”
The simple test at home in private and it comes with step by step instructions. The test looks for hidden blood in your stool, which could be an early sign of bowel cancer.
Almost 42,000 people are diagnosed with bowel cancer each year in the UK and more than 16,000 people die from the disease. It is the nation’s second biggest cancer killer.