The latest word on lung cancer screening was just published in a recent New England Journal of Medicine. In this trial, participants at high risk of getting lung cancer were given either annual chest x-rays or spiral CT scans for three years. There was an annual analysis of new lung cancer cases and deaths in each group.
At the end of the study the results were revealed: those who had undergone regular CT scanning had a 20% reduction in lung cancer mortality. (See graphs below for details.) How can we put this in perspective; is this a game-changer in the cancer detection field?
First of all, the absolute number of lung cancer cases in each group was small, only slightly more than 1% of the participants in each group. With a 20% difference in mortality hundreds of people would need to be screened to reduce mortality by one person. No attempt was made in this trial to assess the cost of saving that life.
The cost far exceeds the cost of the scans because all CT and x-ray abnormalities had to be tracked down, sometimes with invasive procedures like lung biopsy. There has always been the fear among workers in this field that the excess mortality from lung biopsies and surgery for what turned out to be benign findings would outweigh the reduction in cancer-specific mortality. This fear was not realized in this trial. There was very little morbidity from biopsies among those who turned out not to have lung cancer.
This study leaves a number of unanswered questions: Do people at high risk need annual CT’s indefinitely? What is the cost per life saved? Should the groups screened be extended beyond the high-risk groups described in the trial?
The last few months have seen an explosion of information about the benefits of lung cancer screening, previously thought to be a useless exercise in the absence of improved mortality with chest x-rays. Whether all pulmonologists, internists and family practitioners should now feel compelled to offer screening CT scans to people at risk is unanswered at present but I believe that the field is moving in that direction. For better or worse, cost per life saved may also have an impact on public policy decisions in this area of medicine.