共用题干 第二篇CT Scans and Lung CancerSmall or slow-growing nodules（小结节）discovered on a lung scan are unli...

共用题干
第二篇

CT Scans and Lung Cancer

Small or slow-growing nodules（小结节）discovered on a lung scan are unlikely to develop into tumors
over the next two years,researchers reported on Wednesday.
The findings,reported in the New England Journal of Medicine,could help doctors decide when to do
more aggressive testing for lung cancer. They could also help patients avoid unnecessarily aggressive and
potentially harmful testing when lesions（损伤）are found.
Lung cancer,the biggest cancer killer in the United States and globally,is often not diagnosed until it
has spread. It kills 159,000 people a year in the United States alone.
The work is part of a larger effort to develop guidelines to help doctors decide what to do when such
growths,often discovered by accident,appear in a scan.
High-tech（高技术的）X-rays called CT scans can detect tumors一but they see all sorts of other blobs
（模糊的一团）that are not tumors , and often the only way to tell the difference is to take a biopsy（活检）,
a dangerous procedure.
At the moment,routine lung cancer screening is considered impractical because of its high cost and
because too many healthy people are called back for further testing.
Good guidelines could help make lung cancer screening practical,Dr. Rob van Kiaveren of the Erasmus
Medical Center in Rotterdam,the Netherlands,who led the new study,said in a telephone interview.
The team looked at 7,557 people at high risk for lung cancer because they were current or former
smokers. All received multidetector（多层螺旋）CT scans that measured the size of any suspicious-looking
nodules.
Volunteers who had nodules over 9.7 mm in width,or had growth of 4. 6 mm that grew fast enough to more
than double in volume every 400 days,were sent for further testing. Of the 196 people who fell into that category, But of the 7 ,361 who tested negative during screening,only 20 lung cancer cases later developed.
In a second round of screening done one year after the first,1.8 percent were sent to the doctor because they
had a nodule that was large or fast-growing. More than half turned out to have lung cancer.
The result means that if the screening test says you don't have lung cancer,you probably don't,the re-
searchers said."The chances of finding lung cancer one or two years after a negative first-round test were