Monday, December 21, 1998 Published at 23:08 GMT
Detecting the invisible signs of cervical cancer
Not all abnormal cells show up on the average smear
Cells that would look normal in a smear test using current methods conceal hidden abnormalities, according to research published on Monday.
The finding comes as a result of a new technique that could reduce the number of errors in cervical cancer screening.
Recent highly publicised cases of errors in screening have led to thousands of women being recalled for further tests.
This leads to anxiety for the women involved and additional costs for the NHS.
Scientists discovered significant differences between smear samples from healthy women and those with pre-malignant abnormalities and cancer by analysing the chemical composition of cells.
Very often only a tiny fraction of the cells in a suspect smear sample are seen to be abnormal.
Because of this, it is easy for even a skilled screener to make a mistake.
By revealing abnormalities in many more cells, the new method could make errors much less likely.
Researchers at Rockefeller University in New York and the biotechnology company Digilab, in Cambridge, Massachusetts, published their findings in the journal, Proceedings of the (US) National Academy of Sciences.
The technique, called infrared spectroscopy, produces recognisable patterns that reflect the chemical composition of tissues and cells.
Methods in development
The researchers used the system to examine more than 2,000 individual cervical cells from 10 healthy women, seven with the pre-malignant condition dysplasia and five with cervical cancer.
They found striking differences between cells from the normal group and the others.
Cells from the women with dysplasia and cancer that looked completely normal under a microscope had distinct abnormalities.
The findings come less than a week after the NHS National Cervical Cancer Screening Programme gave its backing to trials of liquid-based cytology, a technique that improves the quality of cell samples sent to the laboratory for screening.
A week before that, the Cancer Research Campaign put forward its own proposal for an improved screening technique.