A study I have been following with breath held, has me exhaling in cautious optimism. Regular spiral CT scans in heavy smokers appear to cut lung cancer deaths. The National Cancer Institute released initial data saying they do -- by 20%.
Just as concerns have been raised about screening for other cancers, screening for lung cancer hasn't been a black and white issue. In the past I had written about some of the issues involved in CT screening for lung cancer. Certainly CT scans might pick up abnormalities in the lungs, but could they really save lives?
What Happened in this Study?
Beginning in 2002, the National Lung Cancer Trial (NLCT) recruited 53,000 current or former smokers between the ages of 55 to 74. Individuals who were eligible for the study had to have a history of heavy smoking, defined as 30 pack-years or more of smoking. A pack year is determined by multiplying the number of years smoked by the number of cigarettes smoked daily. For example, this could mean someone had smoked a pack of cigarettes daily for 30 years, or 2 packs daily for 15 years.
These individuals then underwent spiral CT screening or a chest x-ray screening yearly for 3 years. Following this, they were followed for a period of up to 5 years. During that period, 20% fewer lung cancer deaths were found among those who underwent CT screening as compared with those who underwent chest x-ray screening alone. For unknown reasons, overall mortality, that is death from all causes not just lung cancer, was 7% lower in the CT group as well.
Christine Berg, MD, project officer for the study at the National Cancer Institute stated, "This is the first time that we have seen clear evidence of a significant reduction in lung cancer mortality with a screening test in a randomized controlled trial."
What Do the Numbers Mean? What Does 20% Mean to Individuals?
A 20% reduction in deaths can be translated to say that for every 300 people meeting the criteria - current or former heavy smokers - who have spiral CT screening yearly for 3 years - one person will live that would otherwise die.
Screening would seem to be a "no-brainer" in this group, to use my kid's terminology. But before jumping in your car and driving to the nearest radiology department, make sure you talk to your doctor about something we call "false positives."
In this study 25% of the participants were found to have an abnormality in their lungs that later proved to be benign (not cancerous). What this means is further testing, such as radiology tests, and perhaps lung biopsies or even lung surgery. It also meant emotional turmoil as they wondered "what if?" The benefits seem pretty clear for many people, but individuals considering screening should be educated about these possibilities.
What About People Who Haven't Smoked 30 Pack-Years?
A big question remains - and that is defining who will really benefit the most from screening. Would I as a non-smoker, younger than the age group evaluated, benefit from screening? After all, non-smokers can get lung cancer too, and the study showed a reduction in death from causes other than lung cancer.
It is important to keep in mind that this study needs to be analyzed further. The study was done on a high risk population, and simply by taking part in a study, these individuals may be more motivated - or concerned - than society as a whole.
Given that lung cancer is the leading cause of cancer deaths in both sexes in the United States, and that we have an estimated 91 million current and former smokers, the math - the number of lives that could be saved - is staggering. I'm certain that the issue of cost will enter many minds, but, just for today, let's imagine the difference this could make. Haven't we, after all, accomplished more formidable tasks in our country?
Photo:National Cancer Institute, Linda Bartlett (photographer)
National Cancer Institute. News. Lung cancer trail results show mortality benefit with low-dose CT. 11/04/10. http://www.cancer.gov/newscenter/pressreleases/NLSTresultsRelease