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Friday, 11 May, 2001, 00:07 GMT 01:07 UK
Cervical screening 'reducing cancer'
Smears can help save lives
Cervical screening has reduced the number of cases of a certain type of cervical cancer by up to 65%, research suggests.

The finding, by scientists at Imperial Cancer Research Fund, challenges previous studies that indicated screening did not affect this type of cervical cancer.

It has long been known that screening is effective at preventing the more common form of cervical cancer, known as squamous cell carcinoma.

Without screening this currently rare form of cervical cancer could become one of the top five cancers in women in 30 years' time

Dr Peter Sasieni, Imperial Cancer Research Fund
However, there have been doubts about whether screening has any effect on the less common form of the disease, adenocarcinoma.

Cases of adenocarcinoma appear to be on the increase - so it is particularly important to find out if screening makes any difference.

Growing risk

Lead researcher Dr Peter Sasieni said: "Our analysis shows the risk of cervical adenocarcinoma to be 14 times greater in women born in the early 1960s than in women born before 1935.

"Although not fully understood, the exponential increase in adenocarcinoma rates in the seventies and eighties is largely due to greater exposure to the human papillomavirus (HPV) after the sexual revolution in the 'swinging sixties'.

"Women currently in their 20s and 30s are more at risk from this virus because it is spread through sexual intercourse and it's now more common for people to have had several sexual partners."

Dr Sasieni carried out a statistical analysis of the way rates of adenocarcinoma had increased between 1971 and 1987.

They found that by 1996-97 rates of the disease in women aged 25-54 were nearly 65% lower than predicted by their analysis.

They believe this can only be due to the introduction of cervical screening in 1988.

Dr Sasieni said: "Cervical screening has come under a lot of scrutiny lately. We know it's not perfect, but this study does reinforce how effective it can be at preventing cancers.

"Without screening this currently rare form of cervical cancer could become one of the top five cancers in women in 30 year's time."

Rare form

Adenocarcinoma is much rarer than squamous cell carcinoma, which accounts for at least 90% of cases of cervical cancer.

However, it appears to develop much faster, and the prognosis for patients is considerably worse.

The disease affects cells that are deep inside the cervix, whereas squamous cell carcinoma is a disease of cells closer to the outside of the structure.

Some misclassification

Most smear test use blunt spatulas that are designed to detect signs of squamous cell carcinoma, but not to reach less easily accessible adenocarcinoma cells.

Even when adenocarcinoma cells are included in a smear, some pathologists have mis-classified them as squamous cell carcinoma because they have not been trained to tell the difference.

The Imperial Cancer Research Fund is conducting studies on new screening tests for HPV.

The research is published in The Lancet medical journal.

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See also:

03 May 01 | Health
Women died after smear errors
03 May 01 | Health
Smear test errors: The history
03 May 01 | Health
Screening: What should we expect?
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