By- Dr. Joan Marie Pellegrini
Several years ago the National Cancer Institute funded a large trial looking at screening for lung cancer in high-risk patients and the results have been recently released. High risk was defined as amount and length of time of tobacco exposure (1). Patients (2) were randomized to a chest x-ray versus a low dose CT scan annually for three years. The results showed that CT scanning could lead to a 20% decrease in lung cancer deaths. This is mostly because screening patients with CT found many more early stage cancers which could be treated with a cure.
Screening CTs were done annually for three years. In the first year 28% of the studies showed a positive result. This may have been cancer or may have been a benign nodule that needed further workup to decide if it was benign or not. That means that many of the patients had to undergo further testing and procedures as part of their work up.
Prior studies have shown that getting a chest x-ray on every smoker does not decrease mortality. Therefore experts starting thinking about a better screening test and CT scans seems a logical next step.
A regular dose chest CT scan uses approximately 6.5-7 millisieverts (a measure of the amount of radiation exposure). A low dose CT scan uses 1.5 mSv (about a quarter to a fifth as much radiation). A chest x-ray is about 100th the amount of radiation as a low dose CT.
There is no formal lung cancer screening program in Maine yet but several of the larger hospitals have been discussing how best to institute this. There are significant obstacles:
Will insurance pay for it?
How do we identify which patients should be screened?
If the patient is uninsured what will be the cost?
Who will order the study and who will follow up on the results?
There are also many concerns nationally about the cost of health care and screening all smokers for lung cancer would be very costly. However, if we could screen just the right people and lead to better outcomes then the cost would be manageable and justified. In 2011 there were almost 9 million smokers in the US who would fit the criteria for high risk and thus potentially warrant a low dose CT scan. The cost is not just the first CT scan but would also have to include any follow up testing that is needed.
Further studies will be done to better define who would benefit the most from screening CT scans.
Based on this study and its outcomes, I would recommend you have a discussion with your primary care provider about the utility of a low dose CT scan if you believe you are at risk of lung cancer.
1) Patients ages of 55-74 years old with a minimum of 30 years of smoking and no more than 15 years since quitting. New England Journal of Medicine July 18, 2013.
2) 53,000 patients were enrolled between 2002 and 2004 and screening was completed in 2007.