For years and years, lung cancer advocates have often aggressively championed screening for lung cancer, while many in the medical “establishment” and policy-makers expressed reservations that, while there were encouraging indicators of benefit, there was not evidence that lung cancer screening saves lives, so we really couldn’t make a blanket statement encouraging lung cancer screening. That has now changed, as the NCI-sponsored National Lung Screening Trial (NLST) has now been reported to demonstrate a 20% improvement in lung cancer-specific survival. A preliminary but detailed manuscript describing the trial itself is published in the journal Radiology and is available at no charge.
The trial was started in 2002 and randomized over 53,000 patients who were 55-75 and had at least a 30 pack-year smoking history (pack-years being the product of average number of packs of cigarettes smoked per day x number of years smoking) to either annual low-dose spiral CT scans for three consecutive years or a chest x-ray on the same interval. These screening CT scans are done without IV contrast and are done within a single breath hold (up to 15 seconds) but can fully view the lung fields.
The Data Safety Monitoring Committee that regualrly reviews the trial results over the course of a study’s ongoing conduct recently reviewed the most current results and noted a statistically significant improvement in the lung cancer-specific survival of people were were randomized to screening CT scans. Specifically, there were 354 deaths from lung cancer on the CT arm, vs. 442 deaths from lung cancer on the arm assigned to chest x-rays, a 20.3% reduction. In addition, the CT screened patients had a 7% reduction in “all cause mortality” (not just lung cancer, but deaths for any reason), with only 25% of the deaths in the overall trial due to lung cancer. This was likely due to detection of issues such as cardiovascular disease and other incidental but significant medical problems with CT but not chest x-ray screening.
Though it remains to be seen what formal policies will be enacted, these results should be sufficient to lead to a fundamental change in screening policy in the US, and hopefully a change in how the medical community, insurers, and other policy-makers perceive the value of screening for lung cancer. The acid test is improvement in survival, and there is now clear evidence that CT screening for lung cancer saves lives, at least in this particular population.
It is important to bear in mind that these results were seen in a group of people who have been identified as being at higher risk and potential candidates for an intervention. These results don’t necessarily apply to never-smokers or much younger patients, or to people who are frail and/or very elderly and who may not be candidates for the standard curative interventions that we would pursue after detecting a lung cancer. It remains to be seen how the results of the NLST may be broadened to other groups and whether scans will routinely be covered by insurers.
We also need to remember that many lung cancer deaths were not able to be averted with screening, so we need to redouble our efforts to improve treatments once a lung cancer is detected, and to counsel people to quit smoking or to never start, since smoking remains the most significant risk factor. And sadly, some smokers feel exonerated by a clear scan and justified to continue to smoke. Screening is an ideal “teachable moment” to review the risks of smoking not just for lung cancer, but also for heart disease and other issues.
There are also some risks to consider in screening. We don’t yet know of the long term risk of screening, since these results are still the product of just a few years of follow-up. In addition to potentially detrimental radiation effects, we also know that CT scans can detect many lesions that end up not being cancer but that lead to many subsequent scans, a good deal of patient anxiety, and sometimes invasive procedures.
Nevertheless, the results just announced should settle a longstanding debate and lead to a new consensus in the value of CT screening for longtime smokers that promises to reduce the death rate from lung cancer by 20%, and that’s a great prospect as we usher in Lung Cancer Awareness Month, befitting the first exclamation point I’ve had in the title of a post.