Screen Test？？ 1.Every year millions of women are screened with X－rays to pick up signs ofb

Screen Test

？？ 1.Every year millions of women are screened with X-rays to pick up signs ofbreast cancer. If this happens early enough, the disease can often be treated successfully.According to a survey Australia, Canada, the US and Spain, screen women under 50.？？

？？ 2. Butthe medical benefits of screening these younger women are controversial, partlybecause the radiation brings a small risk of inducing cancer. Also, youngerwomen must be given higher doses of X-rays because their breast tissue isdenser.？？

？？ 3.Researchers at the Polytechnic University of Valencia analysed the effect ofscreening more than 160,000 women at 11 local clinics. After estimating thewomen&39;s cumulative dose of radiation, they used two models to calculate thenumber of extra cancers this would cause.？？

？？ 4. Themathematical model recommended by Britain&39;s National Radiological ProtectionBoard (NRPB) predicted that the screening programme would cause 36 cancers perioo,ooo women， 18 0f them fatal. The model preferred by the UN Scientific Committee onthe Effects of Atomic Radiation led to a lower figure of 20 cancers.？？

？？ 5. Theresearchers argue that the level of radiation-induced cancers is"not verysignificant" com- pared to the far larger number of cancers that arediscovered and treated. The Valenciaprogramme, they say, detects between 300 and 450 cases of breast cancer inevery 100,000 women screened.

？？ 6. Butthey point out that the risk of women contracting can？？cer from radiation couldbe reduced by between 40 and 80 percent if screening began at 50 instead of 45,because they would be exposed to less radiation. The results of their study,they suggest, could help "optimize the technique" for breast cancerscreening.

？？7."There is a trade-off between the diagnostic benefits of breast screeningand its ri？？sks," admits Michael Clark of the NRPB. But he warns that thestudy should be interpreted with caution. "On the basis of the currentdata, for every 10 cancers successfully detected and prevented there is a riskof causing one later in life. That&39;s why radiation exposure should be minimizedin any screening pro- gramme. "

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