• 2/10/2005
  • London, England
  • Dr Thomas Stuttaford
  • TimesOnLine

The United Kingdom cervical screening programme, which aims to detect pre-malignant changes in a woman’s cervix so that these may be treated before cervical cancer has formed, is said to be the most successful in the world. Even so, the occasional case of cervical cancer escapes the screening net and there is still a death rate.
Sometimes this is because of a faulty smear-taking technique. The worst case I ever saw of this involved a fellow journalist, who had been reassured about persistent symptoms after the smear was passed as normal. The reassurance, on clinical grounds alone, was obviously misplaced and when the smear was repeated the cervix had tumours in three places, one of which, it transpired at surgery, could not be removed with what is known as an adequate margin.

It is hoped that a vaccine will be prepared, but five years is the target for its introduction. Then it will given to all girls before they become sexually active. However, further advances will be needed before it can be predicted that cervical cancer will be eradicated.

The present vaccines under trial protect against only two of the types of human papilloma virus (HPV) infection, HPV-16 and HPV-18, that regularly cause cancer. These two account for about 70 per cent of cases of cervical cancer. The remaining 30 per cent are caused by other types of HPV, especially but not exclusively HPV-31 and HPV-33. The current advance in vaccine therapy is encouraging for contemporaries of my nine-year-old grandchildren but not of such fundamental importance to older generations.

Cervical cancer is caused by only a few of the hundred or so different types of HPV — also known as wart viruses — that attack the human body. These viruses give rise to the warts that plague children’s hands, the feet of those who walk on gym floors or around damp swimming pools, and even the disfiguring vulval, penile and perianal warts.

Surprisingly, the obvious genital warts are not those that are usually pre-malignant. The malignant warts that attack the cervix, and also the perianal area and penis, are caused by a small minority of wart viruses and the initial lesion looks innocuous.

As HPV is spread by sexual intercourse, it was thought that a freer approach to sexual intercourse would result in an epidemic of cervical cancer. However, despite the changes in sexual mores over the past 40 years, mortality from cervical cancer continues to fall, and even in the past ten years has dropped from 5.1 to 2.9 per 100,000 women.

The need for continued cervical screening will not only be to pick up those cases of malignancy caused by viruses such as HPV-31 and HPV-33, but to detect pre-malignant changes in women who are already infected.

The efficiency of screening is improving and is likely to continue to develop. It is now recommended that smears should be taken by means of liquid-based cytology, which involves using a small, bristly brush rather than a traditional spatula. This modification reduces the number of inadequate smears, such as the one taken from my former colleague, and the need for repeat visits after an initial smear.

The smear test is increasingly often accompanied by the preparation of a culture so that doctors may determine whether HPV is present on the woman’s cervix.

A high percentage of young women are infected with HPV at some stage of their active sexual lives, but usually the patient’s immune system is able to cope with the infection before there are serious irreversible changes in the cervix, and the virus disappears spontaneously.