The National Lung Cancer Screening Trial, which compared the effects of CT screening and standard chest X-ray in smokers, was stopped early because preliminary findings showed clear evidence of a significant reduction in lung cancer mortality when CT was used to screen for lung lesions. CT, or computed tomography, captures three-dimensional views of tissues in the body.
“This study is of vast importance worldwide,” said David Gandara, director of thoracic oncology at UC Davis Cancer Center and president of the International Association for the Study of Lung Cancer, a 4,000-member lung cancer organization. “This is as good as it could have been in terms of a positive result.”
Gandara said the study results represent the first time that a screening test has been shown to definitively reduce lung cancer deaths.
“There have been other studies in the past which have shown a screening test can pick up early lung cancer, but this is the first clear-cut evidence from a randomized, controlled trial that one screening method results in decreased deaths,” he said.
The trial enrolled more than 53,000 current and former heavy smokers ages 55 to 74, who were given either a screening CT scan or chest X-ray, once at the outset of the study and two more times over the next two years. Patients were followed for five years. Researchers found 20 percent fewer lung cancer deaths among trial participants screened with CT. Of the total enrolled in the study, 354 participants who received CT scans died from lung cancer while 442 participants who had conventional X-rays died from lung cancer. The study also found that patients screened with CT had lower death rates from other causes, as well.
Noting that CT scans are costly and may unnecessarily expose people to radiation, Gandara said UC Davis researchers are working on other ways to screen for lung cancer that would have fewer potential side effects.
UC Davis cancer researchers recently won a large Department of Defense grant to find biological markers in the blood that can detect lung-cancer cells. The work is being done in coordination with several other cancer centers in the U.S.
“There is already considerable data that cancer alters certain proteins in the blood, and that there are markers of tumor DNA within the blood,” Gandara said, citing recent UC Davis research that found various mutations in certain genes of patients with advanced lung cancer.
While CT scans would be appropriate for heavy smokers at high risk for lung cancer, Gandara said, a blood test would be a more effective screening technique, especially for people who have never smoked but may have a genetic predisposition for lung cancer.
“There is a now a rising proportion of patients who are never-smokers, and don’t have second-hand smoke exposure who are getting lung cancer,” he said. “These are younger patients, primarily young women, some in their 20s or 30s, and their lung cancer is biologically quite different from smokers’ cancer. We might be able to develop blood tests for all these patients.”
UC Davis Cancer Center is the only National Cancer Institute- designated center serving the Central Valley and inland Northern California, a region of more than 6 million people. Its top specialists provide compassionate, comprehensive care for more than 9,000 adults and children every year, and offer patients access to more than 150 clinical trials at any given time. Its innovative research program includes more than 280 scientists at UC Davis and Lawrence Livermore National Laboratory. The unique partnership, the first between a major cancer center and national laboratory, has resulted in the discovery of new tools to diagnose and treat cancer. Through the Cancer Care Network, UC Davis is collaborating with a number of hospitals and clinical centers throughout the Central Valley and Northern California regions to offer the latest cancer-care services. For more information, visit www.ucdmc.ucdavis.edu/cancer.