NHS cervical screening programme

The aim of the cervical screening programme is to detect pre-cancerous changes in the cervix, and to reduce the incidence of and mortality from invasive cervical cancer. Cervical screening was started in the NHS in 1964, and in 1988 a nationwide, computerised call and recall system was introduced.

The NHS cervical screening programme has been confirmed as a world leader for setting standards in cervical screening (1). Cancer of the cervix is the second most common cancer among women world wide but in the UK it is eleventh. According to the research 4,500 women’s lives are saved each year (6). It is estimated that the introduction of screening prevented an epidemic of cervical cancer and will eventually save some 100,000 British women born since 1950.

All women between the ages of 25 and 64 are eligible for a free cervical smear test every three to five years. In the light of some research into screening intervals the NHS cervical screening programme is now done at different intervals depending on age.

Invitation for the first cervical screening test is at 25 years of age. Between the ages of 25 – 49 smear tests should be done three yearly. Between the ages of 50-64 cervical screening tests should be done five yearly. For women over the age of 65 a test should only be done if they have not been screened since the age of 50 or have had recent abnormal screening tests (7).

Issues in cervical cancer screening

Why are women under 25 and women over 65 not invited?

Screening in younger women can do more harm than good for a number of reasons. Firstly cervical cancer is rare in women under 20. Secondly a teenager’s cervix is still developing, resulting in some young women having an abnormal smear result, and having unnecessary treatment when in fact there is nothing wrong.

Although lesions treated in very young women may prevent cancers from developing many years later, the evidence suggests that screening should start at age 25 (8). Lesions that are destined to progress will still be screen-detectable and those that regress will no longer be a source of anxiety. Younger women will not have to undergo unnecessary investigations and treatments.

If a woman is aged 65 and over and has had three consecutive negative smear tests she is taken out of the call-recall system. The natural history and progression of cervical cancer means it is highly unlikely that such women will go on to develop the disease (8).

The cervical screening test

Another important change in cervical screening is the way the smear test is done. Following recommendation by NICE, liquid-based cytology (LBC) is now being rolled out across the UK.

LBC is a new way of preparing cervical samples for examination and over the next three years laboratory staff and sample takers will be retrained to use this method. Recent pilots have demonstrated that it will reduce the number of inadequate tests (from 9% to 1-2%) and therefore the numbers of women who have to be recalled for repeat testing.

Results have also demonstrated that LBC reduces anxiety in women due to the quicker reporting time, as well as the reduction in the number of women whose tests have to be repeated. In turn it also reduces the pressure on the workforce as they have fewer inadequate smears to look at and clearer samples to report (1).

HPV testing

New tests are being developed to detect the types of human papilloma virus that cause cancer. Studies are also going on to find out whether these tests should be part of the national screening programme to prevent cervical cancer (9).

A new test called the hybrid capture HPV Test has been in trials throughout the USA and UK. This test helps doctors identify women who are most at risk of developing cervical diseases or cervical cancer (9).

The effectiveness of HPV testing alongside the smear is being evaluated as part of the national TOMBOLA study (Trial of Management of Borderline and Other Low grade Abnormal smears). The current position is being kept under review by the advisory committee on cervical screening and the national screening committee. The results of the TOMBOLA trial will be available in late 2006 (10).

Cancerbackup has information about cervical screening.

HPV vaccine

A number of trials have researched vaccines to prevent HPV.

A phase 3 trial (FUTURE II) reported its results in 2005. The trial involved 12,000 women aged between 16 and 26 none of which had HPV at the start of the trial.

Half the group of women received the HPV vaccine Gardasil and the other half received a placebo. The group who received the vaccine did not have any precancerous changes. The placebo group had 21 precancerous changes (0.4%). The research also showed that the vaccine protected over 90% of new infections of HPV and protected against HPV types 6 and 11

Two other phase 3 trials are testing the vaccine Cervarix. The first trial involved 18,000 women under the age of 26 from all over the world including the UK. The study was called PATRICIA (PApilloma TRIal to prevent Cervical Cancer In young Adults). The trial has recently closed and the results won’t be known for some time.

The second Cervarix trial for women aged 26 and over opened in February 2006 and aims to recruit 5,000 women (11).

The results so far have been promising and mean that it might be possible to routinely vaccinate against HPV in the future. These vaccines are not available yet and are still only being used in clinical trials. Although the vaccines are a significant development it may be sometime before they are licensed.  The vaccines won’t impact on the current NHS screening programme and women will still need cervical screening tests.

Quality assurance issues in cervical screening

The NHS cervical screening programme has a quality assurance programme, which is continually being reviewed. There are now quality assurance guidelines available for the management of the entire screening system including:

• the training needs of smear takers
• cytology
• histopathology
• and colposcopy.

These issues are dealt with in the relevant NHS cervical screening programme publications (12, 13).

All women should receive written confirmation of the results of their smear test within six weeks (80% within four weeks).