"Annual CT scans of current and former heavy smokers reduced their risk of death from lung cancer httphealth.nytimes.comhealthguidesdiseasecanceroverview.htmlinlinenytclassifier by  percent a huge governmentfinanced study has found. Even more surprising the scans seem to reduce the risks of death from other causes as well suggesting that the scans could be catching other illnesses. The findings represent an enormous advance http in cancer detection that could potentially save thousands of lives annually although at considerable expense. Lung cancer httphealth.nytimes.comhealthguidesdiseaselungcanceroverview.htmlinlinenytclassifier will claim about  lives this year more than the deaths from colorectal breast pancreatic and prostate cancers combined. Most patients discover their disease too late for treatment and  percent die from it. No screening method had proved effective at reducing mortality from the disease. Four randomized controlled trials done during the s showed that chest Xrays while they helped catch cancers at an earlier stage had no effect on overall death rates. Since then researchers have suggested that CT scans  which use coordinated Xrays to provide threedimensional views  could detect lung tumors httphealth.nytimes.comhealthguidesdiseasetumoroverview.htmlinlinenytclassifier at an even earlier stage than Xrays. This is the first time that we have seen clear evidence of a significant reduction in lung cancer mortality with a screening test in a randomized controlled trial said Dr. Christine Berg of the National Cancer Institute httptopics.nytimes.comtopreferencetimestopicsorganizationsnnational_cancer_instituteindex.htmlinlinenytorg. Cancer doctors and others predicted that the studys results would soon lead to widespread use of CT scans in particular for older smokers who have a one in  chance of contracting lung cancer.  These people are worried about lung cancer and now there is an opportunity to offer them something said Dr. Mary Reid an associate professor of oncology at the Roswell Park Cancer Institute in Buffalo. But health officials involved in the study refused to endorse widespread screening of current or former smokers saying more analysis of the studys results is needed to further identify who benefited most. Such an analysis is months away. And they pointed out that the study offers no reassurance about the safety of smoking httphealth.nytimes.comhealthguidesspecialtopicsmokingandsmokelesstobaccooverview.htmlinlinenytclassifier or the advisability of CT scans for younger smokers or nonsmokers. No one should come away from this thinking that its now safe to continue to smoke said Dr. Harold E. Varmus director of the National Cancer Institute.  Suspicious nodules that may indicate lung cancer can be seen in a CT scan of the lung above but not in an Xray below. Credit Claudia Henschke  Patients wishing to get a CT lung screen will most likely have to pay the roughly  charge themselves since few insurers pay for such scans unless an illness is suspected. The federal Medicare httptopics.nytimes.comtopnewshealthdiseasesconditionsandhealthtopicsmedicareindex.htmlinlinenytclassifier program will soon reconsider paying for such screens a Medicare official said. The study called the National Lung Screening Trial was conducted by the American College of Radiology Imaging Network and the cancer institute. It involved more than  people ages  to  who had smoked at least  packyears  one pack a day for  years or two packs a day for  years. Exsmokers who had quit within the previous  years were included in the group. Each was given either a standard chest Xray httphealth.nytimes.comhealthguidestestxrayskeletonoverview.htmlinlinenytclassifier or a lowdose CT scan httphealth.nytimes.comhealthguidestestctscanoverview.htmlinlinenytclassifier at the start of the trial and then twice more over the next two years. Participants were followed for up to five years. There were  lung cancer deaths among those who received CT scans and  among those who got Xrays. The  million study which began in  was paid for by the cancer institute and carried out at  sites. Its preliminary results were announced days after an independent monitoring board determined that the benefits of CT scans were strong enough to stop the trial. The study will be published in the coming months. The study found that for every  people who were screened one person lived who would otherwise have died during the study. But onequarter of those given CT scans were found to have anomalies nearly all of which were benign. These false signals generally led to more worry more CT scans and sometimes to lung biopsies and thoracic surgery. There are economic medical and psychological consequences of finding these abnormalities Dr. Varmus said. Deaths due to all causes declined by  percent among study participants who received CT scans suggesting the tests helped to detect other lifethreatening diseases besides lung cancer. Dr. Claudia Henschke a clinical professor of radiology at Mount Sinai Medical Center and a longtime advocate for use of CT to screen for lung cancer said the study was likely to have underestimated the benefits of CT scans because participants were screened only three times. Had the screening continued for  years as many as  percent of lung cancer deaths could have been averted she said. Dr. Henschkes research has been controversial because of its statistical methods and its financing which included money from a tobacco company. She earns royalties from makers of CT machines. What we also have found is that lowdose CT scan gives information on cardiovascular disease emphysema httphealth.nytimes.comhealthguidesdiseaseemphysemaoverview.htmlinlinenytclassifier and other pulmonary diseases Dr. Henschke said. Those are the three big killers of older people. There is just tremendous potential. Photo  biology of lung cancer has long suggested that the size of cancerous lung tumors tells little about the stage of the disease. If we look at this study carefully we may suggest that there is some benefit in highrisk individuals but Im not there yet Dr. Patz said. Since  million people in the United States smoke and tens of millions more once smoked a widespread screening program could cost billions annually. Any further refinement of those most at risk could reduce those costs. Lowdose CT scans expose patients to about the same radiation levels as mammograms httphealth.nytimes.comhealthguidestestmammographyoverview.htmlinlinenytclassifier. Little is known about how the cumulative risks of years of such scans would balance the benefits. The studys results could have both legal and political consequences. Suits against tobacco companies have sought to force cigarette makers to pay for annual CT screens of former smokers. But with the science uncertain those claims have so far been rebuffed. Congress has diverted some research money to create pilot CT lung screening programs diversions that may gain momentum now. Some Obama administration officials argued during the debate on the health care law that patients health was often harmed by getting too many tests and procedures that if reduced would improve health while reducing costs. This study suggests that at least in lung cancer spending more on tests saves lives. Laurie Fenton president of the Lung Cancer Alliance which has lobbied for widespread CT lung screening said the debate about the advisability of such scans is now over. The challenge now shifts from proving the efficacy of the method to developing the proper quality standards infrastructure and guidelines to bring this needed benefit to those at high risk for the disease  now Ms. Fenton said. But Dr. Peter B. Bach a pulmonologist at Memorial SloanKettering Cancer Center in New York said no one should rush out and get a CT scan yet because further analysis will better define whom the screening helped. Very soon well have an answer about who should be screened and how frequently Dr. Bach said but we dont have that answer today."