More than 150,000 older Americans were involved in the clinical trial, funded by the National Cancer Institute, with about 16,000 enrolled at Washington University School of Medicine in St. Louis.
Results of the study were presented Wed., Oct. 26, at the American College of Chest Physicians annual meeting and will be published Nov. 2 in the Journal of the American Medical Association.
The study’s results confirm earlier, smaller studies evaluating X-rays for lung cancer screening.
“These findings provide solid evidence that lung cancer screening with chest X-rays is not effective,” says Washington University thoracic surgeon G. Alexander Patterson, MD, the Evarts A. Graham Professor of Surgery. “We need to focus our efforts on preventing lung cancer from developing in the first place. Smoking is a major risk factor for the disease, and encouraging young people not to smoke and smokers to quit could have a real effect on lowering deaths from lung cancer.”
Participants in the study, known formally as the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, were 55-74 years of age. Half were randomly assigned to receive up to four annual chest X-rays, and the other half received usual medical care, meaning that they only got a chest X-ray if their physician thought it was necessary.
Just over 40 percent of people enrolled in the study were former smokers and 10 percent were current smokers.
The researchers followed the participants for up to 13 years but did not find a significant reduction in lung cancer deaths among those who got the annual screening exam: 1,213 lung cancer deaths were observed among participants who got the chest X-rays, compared with 1,230 in the usual care group.
Lung cancers are typically fast growing, and even when detected early by chest X-rays, the tumors are difficult to cure.
The current study follows on the heels of another large U.S. trial at the School of Medicine and other sites, showing that that annual CT scans of current heavy and former smokers reduced their risk of dying from lung cancer by 20 percent, compared to chest X-rays. But health officials have not recommend screening with CT scans even for this high-risk group because of the cost and the high rate of false-positive results.
CT scans provide more detailed images and can find tumors even earlier than X-rays. They also are less open to interpretation by the radiologist reviewing the images, compared to X-rays.
However, Patterson says lung cancer screening with CT may eventually become routine for certain high-risk individuals. But he says more research is needed to determine which patients are most likely to benefit.
Lung cancer is the leading cause of cancer deaths in the United States and worldwide. In 2011, an estimated 221,130 new cases of lung cancer will be diagnosed in the United States, and about 157,000 people will die of the disease.
At the School of Medicine, the PLCO trial is led by Gerald Andriole, MD, chief of urologic surgery at the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital.
Washington University School of Medicine’s 2,100 employed and volunteer faculty physicians also are the medical staff of Barnes-Jewish and St. Louis Children’s hospitals. The School of Medicine is one of the leading medical research, teaching and patient care institutions in the nation, currently ranked fourth in the nation by U.S. News & World Report. Through its affiliations with Barnes-Jewish and St. Louis Children’s hospitals, the School of Medicine is linked to BJC HealthCare.