Even though the efficacy of CT screening in preventing lung cancer deaths was definitively established by a randomized control trial in 2011, very few of those at known high risk have been screened over the last nine years. Recent estimates vary between 2 and 6%.
As described in an earlier page, studies reported in 1986 (chest x-ray) and 1999 (chest CT scan) showed substantially improved survival in screened individuals.
In 2ooo, there was a debate as to what should be done following the findings of the ELCAP study showing that more than 80% of people with lung cancers diagnosed by CT screening were diagnosed in stage 1, when cure rates are generally high. .
The National Cancer Institute (NCI) insisted that a randomized control trial (RCT) called the National Lung Screen Trial (NLST) was needed to prove that lung cancer screening was effective in reducing lung cancer-specific mortality by 20%. They maintained that a RCT was necessary to rule out the fact that a series of “biases “would make screening look more effective and safer than it really was. The study would also determine whether there were risks associated with screening that would outweigh benefits.
Most important, NCI maintained that many of the lung cancers diagnosed by chest x-ray and CT scans were “overdiagnosed”. An overdiagnosed cancer is one that will not cause symptoms or kill during normal anticipated survival. A RCT with 25,000 research subjects in each of two arms was absolutely necessary to rule out such overdiagnosis and prove that lung cancer deaths were reduced by more than 20%.
This idea was outlandish to an experienced surgeon like myself, who had never seen a patient with lung cancer survive untreated for more than five years. I and many others were strongly opposed to delaying CT screening for an estimated ten years just to rule out what I have described as a “preposterous hypothesis”.
The International Early Lung Cancer Action Program (IELCAP) investigators (I was a participant) argued that, given the disparity in stage 1 diagnosis between no screening (15%) and CT screening (80%) was so great, an informed individual would not agree to be randomized into a control arm. Furthermore there was a risk that people randomized to the control arm would “cross-over” by obtaining a CT scan outside the study.
NLST took ten years to prove that CT screening did indeed reduce lung cancer deaths by more than 20% and almost twenty years to prove that overdiagnosis occurred in less than 1%.
Why then has CT screening been provided to so few individuals at risk – after 2011- when NCI advised that CT screening does reduce lung cancer deaths?
I believe that there are a number of reasons.
1. Flaws in NLST research design
2. Misinterpretation of NLST results
3. Stubbornness on the part of cancer screening critics and unwillingness to admit they had been wrong.
4. Cumbersome and slow-moving government regulatory processes.
5. Centers for Medicare and Medicaid Services (CMS) requirement for “shared decision making”,
6. combined with false and misleading information in mandatory “decision aids”.
7. Misguided financial analysis of cost-effectiveness.
8. Research results tainted by tobacco industry potential conflicts of interest.
9. COVID pandemic.
These issues will be discussed in further depth in future pages.
I have had my first lung cancer screening CT scan. What next?