Screening former or current smokers with high-tech scans can significantly cut deaths from lung cancer, according to a long-awaited federal study released Thursday.
The study of more than 53,000 middle-aged and elderly people who either once smoked or currently smoke heavily found there were 20 percent fewer deaths among those who underwent annual screening with a scanning procedure known as a low-dose helical computed tomography (CT) compared with those who got standard chest X-rays.
The findings were so striking that the National Cancer Institute, which helped sponsor the study, halted the National Lung Screening Trial early after a panel of experts notified officials about the clear results of an interim analysis.
"Lung cancer is the leading cause of cancer mortality in the U.S. and throughout the world, so a validated approach that can reduce lung cancer mortality by even 20 percent has the potential to spare very significant numbers of people from the ravages of this disease," said NCI Director Harold Varmus.
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. Although significant advances have been made in reducing deaths from other leading cancers, such as breast and colon cancer, lung cancer has remain stubbornly resistent. The new finding marks the first good news about the disease in decades. There are an estimated 91.5 million current and former smokers in the United States, all of whom are at increased risk for lung cancer.
"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 Christine Berg, who led the study for the National Cancer Institute.
The new findings come after several previous studies have produced mixed results about the usefulness of the screening to try to catch lung cancer in its earliest and most treatable stages. It remained unclear whether the benefits outweighed the risks from radiation from the scans and the dangers, stress and anxiety from unnecessary surgery and other treatment caused by false alarms. But in addition to reducing deaths from lung cancer, the new study found there was a reduction of 7 percent in deaths from any cause among those scanned.
Experts stressed that smoking was the leading cause of lung cancer and the best way to fight the disease was to either never smoke or stop smoking.
"These findings should in no way distract us from continued efforts to curtail the use of tobacco, which will remain the major causative factor for lung cancer and several other diseases," Varmus said.
The study, which started in 2002, involved 53,500 men and women at 33 sites across the country. Participants had to have smoked at least 30 "pack-years," which is calculated by multiplying the average number of packs of cigarettes smoked per day by the number of years the person smoked. They also had to have no signs or history of lung cancer.
The participants were randomly assigned to receive three annual screenings with either low-dose helical CT scans, which are also known as spiral CT scans, or a standard chest X-ray. The CT scans use X-rays to obtain multiple images of the chest. Most hospitals can perform the scans. The subjects were then followed for up to another five years to see who developed lung cancer. Those who were diagnosed received standard treatment.
A total of 354 deaths from lung cancer occurred among the subjects who underwent CT scans, compared with 442 among those who got the chest X-rays - a 20.3 percent reduction in lung cancer mortality.
The findings come as health experts have increasingly been questioning the value of screening for a variety of health problems. In recent years, experts have questioned whether mammography for breast cancer, PSA testing for prostate cancer and Pap smears for cervical cancer were being overused.
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