Ninety-six percent of the patients in the study who were diagnosed with lung cancer through CT scans and had the cancer removed found that the disease did not return, said the study's lead investigator, Claudia Henschke, a radiology professor and head of chest imaging at New York-Presbyterian Hospital/Weill Cornell Medical Center.
The earlier lung cancer is found, the better the patients' chances of survival.
Henschke was to present the findings Monday at the annual Radiological Society of North America meeting in Chicago.
Lung cancer causes most cancer deaths, killing more people than breast, prostate and colon cancers combined, according to the American Cancer Society. The disease is often diagnosed at advanced stages when it is incurable and has an average five-year survival rate of only 15 percent.
CT, or computed tomography, scans allow doctors to find the cancer in its earlier stages. The technology involves scanners that view the lungs and surrounding tissue at different angles and can spot growths that are as small as a grain of rice. The tests cost hundreds of dollars, are usually not covered by insurance and can lead to more diagnostic procedures such as surgery.
The study, called the International Early Lung Cancer Action project, reviewed about 27,000 cases of people who were at a high risk for lung cancer. More than 400 of those patients were diagnosed with cancer, mostly in the early stages. The project began in 1993 and followed patients for an average of four years, Henschke said.
Some doctors worry that CT scans find growths that are not problematic, and can cause patients to needlessly have tumors removed.
The study outlined recommendations for doctors to follow to help ensure that such procedures are not performed on patients who do not have the disease, Henschke said.
"It's a balancing act, you want to diagnose the lung cancer as early as possible and you want to minimalize the procedures for those who don't have it because it's important to avoid unnecessary biopsies and unnecessary surgeries," she said.
The key to keeping survival rates high in lung cancer screening is for patients to receive CT scans regularly, Henschke said.
"To really have the maximum benefit of screening you have to come in year after year," she said.
Some say that because the study did not have a control group who did not get screened by the computerized scans, the results do not prove that CT scans can help save lives.
Most lung cancers do not cause symptoms until they have spread, but some patients experience a persistent cough, chest pain and loss of appetite. If a doctor suspects a patient has lung cancer, a chest X-ray is often conducted to determine whether there are cancerous growths and more procedures typically take place after that to help diagnose the patient.
More lung cancer cases are detected through screening than when they're found through those usual methods of diagnosis, said Paul Pinsky, a statistician with the National Cancer Institute. But it's hard to determine which of the lung cancer cases found in screening would have been fatal.
"When you don't have a control group, you don't have anything to compare it to," said Pinsky, who is involved in the cancer institute's study that compares CT scans with chest X-rays. "Those people might not have died of lung cancer anyway."
Henschke said that a control group is not needed because existing research and statistics show that 85 percent of lung cancer patients who aren't screened die.