Cancer studies show screening success

SCREENING for breast cancer can achieve a 25 per cent reduction in patient mortality. But screening also raises difficult questions about who receives treatment and what treatments should be provided, a conference in Dublin has been told.

These questions will become even more difficult with the advent of advanced genetic screening for diseases, said Dr Sue Moss, head of the cancer screening evaluation unit at the Institute of Cancer Research, Surrey. Genetic screening for predisposition to disease represented an "ethical dilemma she said.

Dr Moss was speaking at the annual Academy of Medical Laboratory Science conference, a two-day event which opened yesterday at the RDS.

Her unit attempts to assess the suitability of a disease for screening. "A screening test is not supposed to be a definitive test," she said. Equally, screening should only be undertaken if an illness is a significant health consideration in a population.

There were costs versus benefits to be weighed up in screening assessments, she said. Costs include financial investment, but also any hazards associated with screening such as X-ray use and the anxiety caused to the person being tested.

The benefits of screening include financial savings, with early diagnosis lending to less costly treatments. There is the reassurance factor for patients, longer life expectancy and the possibility of using less aggressive medical procedures.

She used examples of breast and prostate cancer screening to describe how programmes were assessed. Breast screening was favoured because early diagnosis often meant the disease was less likely to spread, she said.

Large-scale studies in the US and Scandinavia suggest that breast cancer mortality is reduced by an average 25 per cent because of early diagnosis through screening, Dr Moss told delegates.

If screening is introduced then there had to be agreed policies about what represents a positive result. The health service behind the screening must be able to provide both follow-up diagnosis and potential for treatment.

This, however, raised questions about "optimal" treatment. Each illness presented a range of treatment options depending for example on how advanced the illness was. Tests for prostate cancer in older men were often positive, she said, but treatment might be minimal because the disease could remain latent for long periods.