Until recently, we had no recommendations on who or when to screen for lung cancer. Unlike screening tests for cervical cancer and colon cancer, those with risk factors were left to watch for symptoms alone.
And, by the time symptoms are present, nearly 40% of people already have stage 4 lung cancer.
But we now know that screening (low dose CT screening) a certain population of people can result in a 20% lower death rate from lung cancer. In the National Lung Cancer Screening Trial (NLST), this group of people included individuals between 55 and 74 years of age who had at least a 30 pack-year history of smoking, and who either continued to smoke or had quit in the past 15 years.
But what kind of numbers are we talking about? What percent of the population should be screened to take advantage of this 20% reduction in mortality? And - for those people living with lung cancer right now - how many of their cancers would have been detected using these screening criteria?
The answer to the first question is 6.2 percent of the population (over 40 years of age) are eligible for screening based on these guidelines. Doing a few calculations can make this a little easier to understand. If we estimate the current US population at 312 million, around 1.9 million people would meet the eligibility for screening. If the reduction of death rates was similar to that found in the NLST study, 387,000 lives could be saved.
Of course this math crunching makes several assumptions. And I didn't do any calculations to estimate the number of people who would receive false positives and go through unnecessary (and perhaps risky) medical procedures. But seeing these numbers brings hope that we may someday not too far off see reductions in lung cancer deaths due to screening as we have with cervical cancer and colon cancer.
The answer to the other question is 26.7%. Unfortunately, only 26.7% of cancers people are currently living with would have been detected by using these screening guidelines.
What if the guidelines included more people? Again this is speculation since we don't have studies saying that screening people beyond those noted above results in a lower death rate. If the age range for screening was increased from 55-74 to include everyone between the ages of 50 and 79, and and included anyone who has ever smoked no matter how much or for how long, 68% of the cancers people are living with would have been detected, and 30% of the US population would be eligible for screening.
What is the take-away from these numbers?
First, it's exciting to see that, at least for 6% of the population, we now have a screening tool for lung cancer that appears to save lives.
Second, even if we broadened the guidelines and screened 30% of the population, we would still miss 32% of the lung cancers people are living with. And that number is too high. Lung cancer occurs in non-smokers. It happens in never smokers. Until we have a screening test that includes everyone, it's important to have an awareness of the symptoms and signs of lung cancer, and make an appointment to see your doctor if you have any concerns.
- Screening for Lung Cancer - What are the Issues?
- Symptoms of Lung Cancer
- How is Lung Cancer Different in Non-Smokers?
Pinsky, P., and C. Berg. Applying the National Lung Screening Trial eligibility criteria to the US population: what percent of the population and of incident lung cancer would be covered? Journal of Medical Screening. 2012 Oct 11. (Epub ahead of print)