A controversial new study offers the strongest evidence yet that screening smokers for lung cancer with computerized chest scans can save lives, much as mammograms do for women with breast cancer.
CT scans detected lung tumors early, when they hadn't spread, in the vast majority of patients with lung cancer, and those whose early lung tumors were promptly removed had an estimated 10-year survival rate of 92 percent. Those results were superior to the outcomes for lung cancer patients who haven't been screened. Roughly 70 percent typically survive five years if their tumors are caught early, and overall, the five-year survival rate for lung cancer is just 15 percent in the United States, according to the American Cancer Society.
The disease is so lethal largely because it is usually found too late for treatment to do much good. Only 16 percent of the 175,000 cases diagnosed annually in the United States are detected in Stage 1, when tumors are still confined to the lung.
But doctors have long had doubts that CT scans could improve survival and also feared that screening would lead to too many false alarms and unnecessary biopsies. Scans are not now recommended, but many smokers have been paying for them on their own for their peace of mind.
The new study, being published in today's New England Journal of Medicine, strongly suggests there is a survival benefit. But it does not prove the point, because it lacked a comparison group, many scientists say, making it impossible to tell how people would have fared if they didn't receive a CT scan.
Michael Thun, chief of epidemiology of the American Cancer Society, said it's still not clear which group of people will benefit most from preventive lung cancer screening, or whether the technique works as well in the real world as it does in a selective study with experts reading the scans.
"These are very exciting results, but before there can be a recommendation that CT scanning should be the standard of care for people at high risk of lung cancer, you need even stronger data," he said.
Studies in the 1970s found that screening smokers with regular X-rays did not improve lung cancer survival, and such efforts were largely abandoned until 1999, when Dr. Claudia Henschke of New York-Presbyterian Hospital/Weill Cornell Medical Center published a landmark study showing that sophisticated CT scans found far more small tumors than conventional X-rays did.
Her new study extends these results to a larger group of people and reports on survival. Dozens of researchers around the world screened 31,567 people at high risk of lung cancer because they were current or former smokers or had been exposed to a lot of secondhand smoke.
Participants were initially screened between 1993 and 2005, and the vast majority came back for repeated screenings about a year later. Thirteen percent of those who were initially screened and 5 percent who had repeated screenings had suspicious spots that required further testing. Biopsies were performed on 535 patients; 484 were diagnosed with lung cancer, including 412 in the early stage. Most had surgery or chemotherapy.
The estimated 10-year survival rate, regardless of when the cancer was diagnosed or the type of treatment, was 80 percent.
"When you find it when it's small, you can essentially cure most of them," Henschke said.
The scans cost between $200 and $300. Insurers are not covering lung scans because the government does not recommend them.