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【medical-news】CT扫描能发现早期肺癌
CT Scans Catch Lung Cancer at Earliest Stage
10.25.06, 12:00 AM ET
WEDNESDAY, Oct. 25 (HealthDay News) -- In a finding that could change the landscape of lung cancer diagnosis and treatment, new research shows that annual screening using computed tomography (CT) detected lung tumors at their earliest stage in 85 percent of patients.
And when followed quickly by surgery, the 10-year survival rate for this most deadly of cancers soared to 92 percent, according to a study appearing in the Oct. 26 issue of the New England Journal of Medicine.
"We've shown that this saves lives," said study co-author David F. Yankelevitz, a professor of radiology and cardiothoracic surgery at Weill Cornell Medical College in New York City. "What we'd like to see is this brought into the health-care system in some way, and a lot of people have to be involved in this process. All of the other issues have to come up -- who gets it, how frequently, who pays for it, and this needs to be a dialogue amongst lots of people."
The study results prompted strong reactions throughout the medical community.
"The findings are quite impressive," said Dr. Robert Smith, director of cancer screening at the American Cancer Society. "The results are from multiple institutions and show that the model that they have for screening can be exported and successfully applied in other settings."
"It's a major, major finding," said Dr. Len Horovitz, a pulmonary specialist with Lenox Hill Hospital in New York City. "If you get somebody at stage one, you're basically saying that you can cure them of lung cancer, which is our number one [cancer] killer and usually is diagnosed all too late."
Lung cancer is the leading cause of cancer deaths. Because of a lack of adequate detection methods, malignancies are often diagnosed at an advanced stage. While the five-year survival rate among patients with stage I lung cancer is about 70 percent, it is only 5 percent among those with stage IV disease. Unfortunately, stage I diagnoses are rare.
In 1993, the Early Lung Cancer Action Project (ELCAP) found that, with annual screening with spiral computed tomography (CT), more than 80 percent of persons diagnosed with lung cancer had stage I disease. What investigators didn't know, however, was whether early intervention was effective enough to justify screening large numbers of asymptomatic people at risk for lung cancer.
This latest study involved screening 31,567 asymptomatic people who were at risk for lung cancer either because they had a history of cigarette smoking, had had occupational exposure, or had been exposed to secondhand smoke. Investigators then estimated the 10-year survival rate among those with stage I lung cancer.
Of the total group, 484 participants were diagnosed with lung cancer, 412 of them (85 percent) with stage I disease. Within this subgroup, the estimated 10-year survival rate was 88 percent. Among the 302 participants with stage I cancer who underwent surgery within one month of diagnosis, the survival rate was 92 percent. The eight participants who did not receive treatment died within five years of their diagnosis.
"Survivability at 10 years was 88 percent if it was stage I, and the easiest way to find this is spiral CT," Horovitz said. "If you can pick them up early, you can certainly cure them for 10 years, if not for life. By the time symptoms show up, it's much, much harder."
Screening was even more valuable for people who were at the highest risk (for example, older people and former and current smokers).
The cost of a low-dose CT is below $200, the study authors stated, while the cost of surgery for stage I lung cancer is less than half the cost of late-stage treatment.
The technology is already available and being used, Smith said, although it's not formally recommended by any expert group.
"There's no doubt in my mind that radiologists and others who deal with individuals at high risk for lung cancer are probably adapting this for their own institutions," he said.
The expert panels, however, will likely wait for the results of several ongoing large, prospective randomized trials before making a definitive judgment, Smith added.
Another expert also added a note of caution.
While the study confirms that CT detects small nodules, and that small nodules deemed as early-stage cancer are highly treatable, the trial does not determine the effectiveness of CT scans in reducing mortality among patients at risk for lung cancer, Dr. Edward Patz, the James and Alice Chen Professor of Radiology at Duke University Medical Center, said in a statement. The findings validate prior studies, but do not say how patients would have fared if they had not received a CT scan, he noted.
And CT scans can potentially harm patients by exposing them to repeated, unnecessary radiation or unnecessary surgeries that carry substantial risks, he added.
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作者:admin@医学,生命科学 2011-02-19 05:14
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