CT scans of smokers cut lung cancer deaths
Friday, November 5, 2010
Screening smokers and ex-smokers with high-tech CT scans has been shown for the first time to significantly cut deaths from lung cancer, the leading cancer killer, federal health officials said Thursday.
A long-awaited study of more than 53,000 middle-aged and elderly people who once smoked heavily or currently smoke heavily found 20 percent fewer deaths among those who underwent annual screening with a procedure known as low-dose helical computed tomography (CT), compared with those who had standard chest X-rays.
The findings were so striking that the National Cancer Institute, which sponsored the study, halted the National Lung Screening Trial early so that the public and the study participants could be alerted .
"This finding has important implications for public health with the potential to save many lives among those at greatest risk for lung cancer," said NCI Director Harold Varmus. "This finding will be an important factor in subsequent efforts to protect the tens of millions of former and current smokers in this country against the lethality of lung cancer."
Lung cancer strikes more than 196,000 Americans a year and kills more than 159,000 - more than breast, colorectal, pancreatic and prostate cancers combined. Significant advances have been made in reducing deaths from other cancers, but lung cancer remains stubbornly resistent, and most patients die. There are an estimated 91.5 million current and former smokers in the United States, all of them at increased risk of lung cancer.
Benefits and risks
A CT scan creates a three-dimensional image of the lungs, instead of the two-dimensional perspective captured by a chest X-ray. A scan is more likely to spot a tumor while it is still small and relatively susceptible to removal by surgery, boosting the chances of the patient's survival.
The findings were hailed by the American Cancer Society, the American Lung Association and others.
"With this positive trial result we have the opportunity to realize the greatest single reduction of cancer mortality in the history of the war on cancer," James L. Mulshine, a research official at Rush University Medical Center in Chicago, said in a statement issued by the Lung Cancer Alliance.
Even though CT scans can be performed by most hospitals, experts stressed that it is too soon to issue specific recommendations about the use of CT screening for lung cancer. More analysis is needed to identify who might benefit - perhaps those people who smoked less heavily - and how often patients should be screened, they said.
Some expressed concern that the findings might lead to an increase in the number of people undergoing unnecessary screening. The scans found abnormalities in about 25 percent of those screened, but most turned out to be false alarms.
"As with any study of screening, there are also potential harms to be considered, such as potential overdiagnosis and needless surgeries," said Otis W. Brawley, the American Cancer Society's chief medical officer. "We have learned from the long-term analysis of other screening tests, such as mammography, that it is important to consider both benefit and harms associated with the test."
Health experts increasingly have challenged the value of screening for a variety of health problems. In recent years, they have asked whether mammography for breast cancer, PSA testing for prostate cancer and Pap smears for cervical cancer were being overused, subjecting patients to needless tests and treatment.