SCREENING women aged 50 to 69 for breast cancer does save lives, according to the World 午夜福利1000集合 Organization. But the benefits of mammography for younger women are less clear-cut. There is also no evidence that manual breast examination by doctors or women themselves does any good.
There has been a big debate about whether mammography is worthwhile since two Danish researchers questioned the validity of studies suggesting that it is effective (New Scientist, 15 January 2000, p 3). Now the International Agency for Research on Cancer (IARC) in Lyon, France, which is funded by the WHO, has reviewed all the available scientific evidence.
It concludes that a woman of 50 who is screened every two years will cut her risk of dying of breast cancer by 35 per cent. In Britain, 20 out of 1000 women aged 50 will get breast cancer within the next decade, and of these six will die. Screening reduces the death rate to 4 in 1000. 鈥淚t鈥檚 not a huge benefit but it鈥檚 definite,鈥� says Valerie Beral, one of the report鈥檚 authors, who chairs the British government鈥檚 Advisory Committee on Breast Cancer Screening.
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But women still face a trade-off. Those who are screened can undergo unnecessary treatments, because mammograms can detect tumours that wouldn鈥檛 have produced symptoms during a woman鈥檚 lifetime. Screening can also throw up false positives, causing great anxiety. And the X-rays used for mammography can themselves cause a tiny number of cancers.
But Beral still thinks the benefits outweigh the costs. Women should be informed of the facts so they can make up their own minds, she says.
When it comes to manual breast examination, the group concludes that organised programmes do not bring survival benefits, though it says more studies are needed.