A study of heavy smokers found 20 percent fewer deaths with an annual spiral CT scan.
High-tech imaging scans of heavy smokers have proven so successful in preventing deaths from lung cancer -- the nation's top cancer killer -- that researchers cut short a federally funded trial of the practice to report the news.
The National Cancer Institute reported Thursday that there were 20 percent fewer deaths among study participants who received regular screening with spiral CT scans compared with standard chest X-rays. Even more surprising, the scans seem to reduce the risks of death from other causes as well.
The University of Minnesota and Mayo Clinic played major roles in the study, contributing 6,600 patients and 1,200 patients, respectively, to the national study of 53,000 current or former heavy smokers.
The findings represent an enormous advance in cancer detection that could potentially save thousands of lives annually, although at considerable expense. Most patients discover their disease too late for treatment, and 85 percent die from it.
To date, no screening method has proved effective at reducing mortality from the disease. "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.
Lung cancer strikes more than 196,000 Americans each year and kills more than 159,000, accounting for nearly one-third of all cancer deaths. It is most often diagnosed at advanced stages, and the average five-year survival rate is just 15 percent.
Although significant advances have been made in reducing deaths from other leading cancers, lung cancer has remained stubbornly resistant. The new finding marks the first good news about the disease in decades. There are an estimated 91.5 million current and former U.S. smokers, all of whom are at increased risk for lung cancer.
"For 50 years, people have been trying to see if there is a way to decrease mortality from lung cancer," said Dr. Stephen Swensen, the lead researcher of the Mayo portion of the study. "We've always come up short, so it's real exciting to have the best science ... show we can actually save lives here."
A future rise in CT scans?
Cancer doctors predicted that the results of the study, which began in 2002, would soon lead to widespread use of CT scans, in particular for older smokers, who have a 1 in 10 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 officials involved in the $250 million study refused to endorse widespread screening, saying more analysis of the study's 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 or the advisability of CT scans for younger smokers.
"No one should come away from this thinking that it's now safe to continue to smoke," said Dr. Harold Varmus, director of the National Cancer Institute.
Said Dr. Edward Patz Jr. of Duke University, who was on the committee that helped design and oversee the study: "We want to make sure what we recommend is appropriate rather than everybody going out and asking for it."
Patients wishing to get a CT lung screen will most likely have to pay the $300 to $400 charge themselves, since few insurers pay for such scans unless an illness is suspected. The federal Medicare program will soon reconsider paying for such screens, a Medicare official said.
One in every 300 saved
The findings come after several previous studies have produced mixed results about the usefulness of the spiral CT scans, where a rotating scanner views the lungs at various angles to spot growths when they're about half the size that a standard chest X-ray can detect.
The latest study enrolled people ages 55 to 74 who puffed the equivalent of a pack a day for 30 years. They had one scan a year -- spiral CT or a standard chest X-ray -- for three years, and then had their health tracked.
The study found that for every 300 people who were screened, one person lived who would otherwise have died during the study. But one-quarter 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.
Then there's the radiation question. The study used low-dose CTs, equivalent to the radiation from a mammogram but still higher than from a standard X-ray, researchers said. Regular CT scans used to diagnose suspicious spots can emit far greater radiation levels.
"There are economic, medical and psychological consequences of finding these abnormalities," Varmus said.
However, deaths due to all causes declined by 7 percent among study participants who received CT scans, suggesting the tests helped to detect other life-threatening diseases.
An emotional debate
Cancer screening can be an emotional and controversial subject. Doctors have disagreed on the utility of the so-called PSA test for prostate cancer in older men and breast cancer advocates and survivors were furious last year when a federal task force recommended that routine mammograms start at age 50 -- and not at age 40 as previously suggested.
In this case, Swensen said people might argue over spending money on lung cancer screening when smoking prevention might be more effective.
Dr. Claudia Henschke, a clinical professor of radiology at Mount Sinai Medical Center and an advocate for use of CT to screen for lung cancer, said the study was likely to have underestimated the benefits. Had the screening continued for 10 years, as many as 80 percent of lung cancer deaths could have been averted, she said.
But Patz said he was far from convinced, saying the biology of lung cancer has long suggested that the size of cancerous lung tumors tells little about the stage of the disease.
The U of M offered another caution, that the trial participants -- by definition of their willingness to take part in the study -- may be more health conscious than other smokers. That means they might be more likely to follow doctors' orders and take necessary steps to overcome lung cancers than smokers in the general population, said Timothy Church, a research who led the U of M's arm of the study. But he stressed proving that screening can reduce deaths "is the key. If you can't show this, all of the other questions are useless chatter."
Staff writer Jeremy Olson, the New York Times, Washington Post and Associated Press contributed to this report.