Four in every 10 young women in Oxfordshire are failing to have smear tests to detect cervical cancer.

County public health workers are now urging 25- to 29-year-olds to treat the screening programme like a pension, because the earlier they start the more beneficial it will be for their future.

Since January, cervical smears have been offered to women aged 25 to 49 every three years, and to 50- to 64-year-olds every five years.

GPs and practice nurses are expected to carry out tests on at least 80 per cent of women within those age groups.

But latest county figures show that between March 2000-March 2005, only 61.4 per cent of 25-29 year olds were screened.

Cathy Lines, head of screening for Oxfordshire, said although cancer of the cervix was a slow-growing disease, most cases were caused by viruses introduced during sex. As most women become sexually active in their late teens, abnormalities -- which can develop into cancer -- will start to show in their late 20s.

She said: "There is much more sexual activity in that age group, and although we don't pick up many cancers from screening, we can find the very aggressive early stage to cancer.

"The number of cancers is small, but through smear tests we can stop the abnormalities developing into cancer. If these women don't get screened, these cells are likely to turn into cancer in their 30s and 40s.

"It's a long-term investment in your health, like a pension really -- it's better to start sooner rather than later."

During a smear test, a small sample of cervix cells is taken during an internal examination.

Ms Lines added: "A smear test is not something young women find easy the first time.

"Also, they don't think it will be a problem, and see cancer as something that affects older age groups."

NHS health manager Angela Baker added: "I think there are quite a lot of myths about what happens when you have a smear test, all of which are not true. It doesn't hurt and it could save your life."

More information about cervical smear tests is available from GP practices.