Future of Medicine: Lung Cancer Screening

Lung cancer remains the number one cancer killer in the United States.  Unlike breast cancer, colon cancer and prostate cancer, there is no current screening test for lung cancer.  Screening tests try to find hidden, asymptomatic disease in time to intervene while the cancer is still curable.  Plain chest X-rays have been advocated in the past for lung cancer screening, but yearly chest x-rays do not reduce the death rate from lung cancer.  A recent study of low-dose CT (computed tomography) scans of the chest did show the ability to reduce deaths from lung cancer by 20%, probably by finding tumors at an earlier stage than if no CT was done.

”There was a 20% reduction in lung cancer mortality when you compared CT to X-ray,” says Constantine Gatsonis, PhD, a lead statistician in the analysis for the study and a professor of biostatistics at Brown University in Providence, R.I.

Sponsored by the National Cancer Institute, the National Lung Screening Trial (NLST) was halted early after the trial’s independent Data and Safety Monitoring Board notified the NCI that the data accumulating made it clear that the CT technology for lung cancer screening was superior to the standard X-ray in reducing deaths from lung cancer.

This study included 53,000 past and current smokers with significant smoking history, between the ages of 55 and 74.  The amount or radiation from the CT scan was equivalent to the dose of radiation from a mammogram.   Past studies of CT scans to screen for lung cancer had not shown the ability to reduce the number of deaths from lung cancer, so this study offers new hope.    When lung cancers are found when they are small and before they have spread to other organs, they can be successfully treated with surgery.  Unfortunately, most lung cancers today are found after they have spread elsewhere in the body, making them incurable with current therapies.

Before any test becomes a widely-used screening test, more studies will have to be done to continue to provide evidence that this intervention will truly save lives and money.  There are 94 million past and current smokers in the United States all of whom are at risk for developing lung cancer.    This study tested only smokers,  and people who have never smoked will not benefit from this screening test.   From the New York Times, Dr. Otis W. Brawley, chief medical officer of the American Cancer Society:

We really need to weigh the harms associated with screening,” he said. “The scientific community still needs to digest this. To take a trial that involves people at high risk for lung cancer and to extrapolate it and say it’s good for people with intermediate or low risk is not appropriate.”

The way to truly stop this terrible scourge is to get everyone to stop smoking.