Dr. Adam Goldstein shares his thoughts on new data from the National Lung Cancer Screening Trial.
The National Lung Cancer Screening Trial reported this week that CT (CAT Scan) screening reduced lung cancer mortality by 20% in smokers and former smokers screened with the test compared to those who were not (but only got a chest x-ray). The clinical research was ended early, because the sponsor of the trial, the National Cancer Institute, thought the benefits were too great to continue the research study, particularly because overall mortality for those undergoing screening was also 7% less. Starting today, hundreds of thousands of smokers across the U.S. and millions across the world will start asking their physicians whether or not they should get regular, annual CT scans of their chest. Many Radiology Centers across the U.S. have already started promoting CT screening services to smokers, less than 24 hours after the results appeared.
I have three comments:
1) As Clinical Director of UNC’s Nicotine Dependence Program, I have treated thousands of smokers over the years. The number one treatment is not an annual CAT scan to detect lung cancer, but instead, it is to QUIT SMOKING. Do it now, do it often, do it with friends and family, do it with support from your physician, do it with support from any of the 50 state quitlines throughout the U.S., with free counseling available at 1-800-QUITNOW. Quitting smoking is the only proven method to lower your risk of contracting all smoking-related illnesses, not just lung cancer. Even if you successfully treat lung cancer early, if you don’t quit, your risk of dying from that cancer, or getting a second cancer, are really high. Quitting smoking is the only treatment known to delay the onset of Chronic Obstructive Pulmonary Disease (COPD) or emphysema among heavy smokers. Quitting smoking reduces your risk of heart attacks by 50% within one year, one of the major causes of death from smoking.
2) For smokers wanting to get CAT scans to potentially diagnose a lung cancer early, many more questions than answers currently exist. For instance, the study only screened heavy smokers between ages 55-74. Smokers younger than this age undergoing screening may receive no benefit, or it may take 20 CAT scans over 2 decades to pick up the benefit. In fact, estimates are that you would have to screen almost 300 patients annually with annual CAT scans over at least three years smoke to prevent one cancer death. That also means 299 patients will not benefit from this screening. Thus, you need to be aware of the side effects of screening if you as a patient or a physician decide to pursue it. The false positive rate of CAT scans of the chest in long-time smokers is really high. In the lung cancer trial, 20-60% of patients getting CAT scans had abnormal test results that turned out not to be lung cancer. For these patients, this may involve getting more CAT scans and biopsies even, unnecessarily. So, we may expect that for every lung cancer death initially prevented, 150 patients will undergo fairly invasive tests and risk side effects. These same 299 patients that receive CAT scans receive radiation, and for those who need follow-up studies, they may receive dye that can be harmful. Receiving multiple scans over multiple years in and of itself raises the risk of cancer. For all smokers, even those between the ages of 55-74, the chances of getting a false positive result far exceed the chances of it being a true positive.
3) Consider the costs. To save one life in this study, it will cost over $200,000. Compare that cost to that of smoking cessation, with estimates of $500-$2000 for a successful quitter. Thus, for every patient that we temporarily save, we will get from 100-400 similar patients to quit smoking, an intervention that pays many more long term dividends. Also, no bad side effects occur to anyone else in smoking cessation.
My bottom line: If you are a heavy, older smoker that still smokes, or recently quit, talk with your doctor about your preferences and their recommendations for you. Consider the costs of screening, the potential extra radiation, the likelihood of false positives, and the likely absolute chance that you may not benefit, compared to the lower risk of lung cancer and overall mortality if you do have a lung cancer picked up by this method. Consider how screening for lung cancer will effect your quality of life, and whether you will decide to not quit smoking if your CAT scan is negative?