Spiral CT Scans For Lung Cancer Screening: High Cost, Modest Benefit
A new study has shown that spiral CT scan screening of heavy smokers can reduce deaths from lung cancer. The study looked at 53,000 heavy smokers aged 55-74. Patients were screened with either chest x-rays or spiral CT scans. There were 354 deaths in the CT group vs. 442 deaths in the x-ray group over an eight-year period. The difference was significant, but it is not clear whether spiral CT scans should be used as a standard-of-care screening test in this population. Concerns such as radiation risk and false positives warrant further exploration, but for now I will look at the costs.
Sources put the cost of a CT scan between $300 and $400. Let’s split the difference and call it $350. The study was randomized, so assume that 26,500 people had CT scans at a cost of $9,275,000. This resulted in 88 fewer deaths, or a preventive cost of $105,397.72 each. Does this number have meaning? A common cost/benefit reference for costly treatments, such as cancer therapy, is $50,000 per year of life gained. It seems likely that this test would be cost effective by this standard, since odds are good that those 88 individuals should live another 2 yrs each, many quite a few more.
The study probably represents an incremental benefit against lung cancer. The scan does nothing to the biology of the disease, but it increases the odds of successful treatment with earlier detection.
The statistics can be looked at from another angle, one which makes the CT test seem less attractive. To prevent 88 deaths, 26,500 people were screened, or about 300 scans per single death prevented. Preventing 20% of the 159,000 yearly deaths from lung cancer would save 31,800 lives. But, it would require CT scans of 9.5 million people at an annual cost of more than $3 billion.
To be fair, my analysis does not take into account the cost implications of preventing these deaths, nor does it address the costs of chasing false positive scans or several other “what if” scenarios.
These types of analyses will become necessary for many types of treatments and tests as we convert healthcare to a much more evidence-based system than we currently have.
Lung cancer is a nasty disease with nasty outcomes, and smoking is a very hard habit to break. The question of how much to spend on smoking cessation efforts and how much to spend on detection and treatment of lung cancer is not an easy one.
The National Lung Screening Trial
- Study: CT scans cut lung cancer deaths (boston.com)
- CT Scans of Smokers Cut Lung Cancer Deaths 20% (webmd.com)