Published: 14/04/2005, Volume II5, No. 5951 Page 33
The issue Preventing cervical cancer is a public health priority.
The cervical screening programme is well established but there are concerns about false negatives as well as the inability to reach certain sectors of the community.
Screening is never the whole solution to a problem and it is always important to try to prevent a condition developing in the first place. Unfortunately the major risk factors for cervical cancer relate to sexual habits, and changing such behaviour can be very tricky.
An alternative approach to primary prevention was highlighted by the discovery of an association between human papillomavirus (HPV) and cervical cancer in the 1970s. It now seems likely that two HPV types (18 and 16) cause 70 per cent of all cervical cancers and it has recently been suggested that immunisation against these HPV strains could prevent a large number of cases of cervical cancer.
A double-blind, randomised placebocontrolled trial was undertaken to assess whether vaccination against HPV-16/18 was effective against cervical HPV infection and associated cytological abnormalities.
A sample of 1,113 women aged 15-25 with no more than six sexual partners and no history of cervical abnormalities or evidence of HPV infection were chosen to receive the HPV-16/18 vaccine or placebo. The vaccine or placebo was administered at zero, one and six months and patients were then followed for up to 27 months.
The vaccine was 95 per cent effective against persistent HPV infection and 93 per cent effective against cytological abnormalities associated with HPV.
Other than symptoms at the site of injection there were no differences in side effects between the active and placebo vaccines.
This trial demonstrates that HPV immunisation holds great promise as a mechanism for primary prevention of cervical cancer.
But further work is now needed to assess whether HPV immunisation ultimately protects against invasive cervical cancer.
Once this is done, consideration will need to be given to issues such as the age at which people should be immunised and whether the vaccine should be administered to both sexes.
Vaccination, like screening, is not perfect and patients should be made aware of the possibility that it could fail to induce an immune response.
Women should continue to be encouraged to report significant symptoms such as abnormal vaginal bleeding to their GP, irrespective of any screening result or immunisation history.
Harper DM, Franco EL, Wheeler C et al. Lancet 2004; 364: 1757-1765.
www. thelancet. com Nick Summerton is a GP and PCT medical director.