Lung Cancer Screening; Is It Ready for Primetime?
The general public is witness to frequent debates in the medical world about the risks/benefits and recommendation/non-recommendation of cancer screening procedures. One committee says that prostate cancer screening by routine annual PSA testing saves lives, while another one says that it does more harm in over-diagnosis/over-treatment. Every 2-3 months the news media discusses the ongoing debate over mammography in asymptomatic 40-year old women. Some say it clearly saves lives. Others argue that it does not save lives but unnecessarily adds to rapidly increasing medical costs.
Well, now there is a new cancer-screening strategy in the adult medicine world for lung cancer. This is a major statement for two reasons: 1) The lung cancer survival rate overall is only 15 percent and has not meaningfully improved in the last 40 years. 2) The total number of lung cancer deaths per year (160,000) exceeds breast, colon, prostate, and pancreas cancer deaths combined.
Screening for the non-small cell form of lung cancer has been tried before by annual chest x-rayin high-risk smokers, and failed to show that at the end of five years more people were alive because of screening. There was a hint that it could allow us to diagnose some patients earlier with more surgically curable diseases, but we needed a better tool to examine all the little things that hide in the chest. The CT scan of the chest using a low dose radiation technique was the answer to this chest x-ray shortcoming. On a new CT machine, we can visualize abnormalities in the 3-5 mm sizewith good resolution.
The NLST (National Lung Screening Trial) was started in 2002 and its goal was to determine in 54,000 high-risk smokers aged 55 to 74 whether annual chest CT screening could reduce lung cancer death compared to chest x-ray imaging done annually. The results of this landmark study were published in 2011 in the New England Journal of Medicine. After a healthy debate, the conclusion is now accepted that CT screening reduced lung cancer death by 20 percent.
This is a dramatic result that is flying under the radar in health news. In addition to the planned lung cancer benefits which we believe to be long-term cures, there was an unexpected discovery ofclinically important cardiac disease, vascular disease, lung and esophageal problems, which were unknown. Although I feel this beneficial strategy is ready for prime time now, skeptics do have issues with the study conclusions and its widespread implementation across the country.
1) It is only one study that, although well done and exhaustively analyzed, could have mislead us by chance. A second confirmatory trial would always make us feel more confident.
2) About 30 percent of screens had an initial suspicious abnormality of which 96 percent were not cancer. So false-positive findings were the vast majority; and correctly sorting out the false positives from the true positives will pose a day-to-day struggle for patients and their screening team.
3) The cost of saving each life is estimated to be an additional $240,000. This figure has a wide error range depending on your models’ assumptions, but it is considered acceptable by most experts.
There are two key caveats about the study and its adoption in the community oncology center. First, screening is limited to the highest risk groups for lung cancer, which includes men and women aged 55 to 74 with greater than 30 years of smoking and less than 15 years cessation. Patients aged 50 and older with greater than 20 years of smoking and one additional risk factor may also benefit from screening. These guidelines for who to screen must be strictly followed in order to justify the cost, radiation exposure, and potential complications of diagnostic procedures. Second, lung cancer screening requires a dedicated team approach, including a CT Radiologist, Pulmonologist, Oncologist, and at times a Thoracic Surgeon. Even with all these experts, a complex algorithm of management has been designed to find that one cancer, which may be hiding among the benign scars and benign nodules in a smoker’s lungs.
I highly recommend the NCCN.org website for a more detailed review of these issues. Lastly, please help a smoking friend or family member quit. Because if no one smoked, we would not need lung cancer screening at all.