All women aged between 25 and 49 should be offered cervical screening every three years, leading experts have concluded.
Smear tests save lives
However, they say that every five years is regular enough for women aged 50 to 64.
Until now there has been no precise direction on how often screening should be offered - it has been left to individual health authorities to decide.
According to the most recent figures, 60% of health authorities offer screening every three years, while the remaining 40% opt for either five-yearly screening or a mixture of the two.
Despite this, figures released by National Statistics reveal that in 2002, 927 deaths from cervical cancer were registered in England - the first time the figure has fallen below four figures.
Researchers based their recommendations on an audit of the NHS Cervical Screening Programme.
A programme based on our recommendations offers over 80% protection against cervical cancer for both age groups
They examined the screening histories of nearly 4,000 British women, including 1,300 who had been diagnosed with cervical cancer.
The researchers found that screening every three years offers 84% protection against cervical cancer compared with 73% with five-yearly screening in younger women.
In older women, however, the audit shows very little difference between screening every five years and every three years. Even screening annually was little better than five yearly screening.
Picking up changes
Screening works by picking up potentially cancerous changes, called cervical intraepithelial neoplasia (CIN), which can be removed to prevent cancer progression.
Women under 25 years should not be screened
Women aged 25 to 49 should be screened every three years
Women aged 50 to 64 years every five years
Women over 65 should only be screened if they have not been screened since the age of 50
Around 90% of cases of CIN are diagnosed in women under the age of 45.
Lead researcher Professor Peter Sasieni, of the Wolfson Institute, London, said: "It would seem that cervical cancers in older women tend to develop much more slowly than tumours in younger women.
"In addition, cervical screening is much more effective in women over 50 and that's why they need only attend for screening every five years.
"A programme based on our recommendations offers over 80% protection against cervical cancer for both age groups."
Screening is routinely offered to women from age 20 and some doctors encourage younger women to be screened, if they are sexually active.
However, the new study questions the value of screening women below the age of 25.
Cervical cancer is very rare in women under 25 and screening this age group picks up a great deal of false positives women who appear to have early signs of cancer but in fact do not.
Experts believe that the benefits of picking up such a small number of cases are outweighed by the stress caused by so many false diagnoses.
Professor Sasieni said: "By offering screening in the most efficient way we believe we can prevent the great majority of cervical cancers in women who take part in the programme, while reducing the numbers needlessly referred to a gynaecologist for further investigations."
Dr Richard Sullivan, of Cancer Research UK, said: "The incidence of cervical cancer dropped by 42% in the five years following the introduction of the screening programme.
"We know that every year cervical screening saves lives and we continue to urge women to attend for screening.
"This new research shows us how the programme can be refined and how resources can be maximised to benefit women."
Julietta Patnick, director of the NHS Cancer Screening Programmes, said the recommendations would be assessed by the Advisory Committee on Cervical Screening.
She said: "The NHS Cervical Screening Programme has always used sound research evidence where it is available.
"We are always looking for ways in which we can improve the quality of the programme and offer greater protection for women, while protecting them from over screening."
The research is published in the British Journal of Cancer.