We wanted to look at differences in the stage at diagnosis between younger and older lung cancer patients and median survival between younger and older lung cancer patients and specifically look at how the stage at diagnosis and survival has changed over the last decade, particularly with the onset of lung cancer screening in the US in December 2013. So we used the National Cancer Database, which is one of our big cancer registries in the US that covers about 65% of all lung cancer cases diagnosed in the US each year, and the United States Cancer Statistics dataset, which is a population-based registry which captures about 99% of all lung cancer cases diagnosed in a year.
What we looked at was, one, are younger patients more likely to be diagnosed with later stages of lung cancer? Two, how has that changed over time from 2010 to 2018? Three, what’s the survival rate of patients diagnosed with lung cancer and how does that differ between younger and older patients? And then, four, how has median survival over the last decade changed among younger and older patients, particularly with the NCCN’s recommendation for genetic testing for EGFR and ALK mutations and the approval of immunotherapies in 2015?
What we found is that there is a huge difference in the stage of lung cancer diagnosis between young and older patients with younger people being much more likely to be diagnosed with late stage disease. Among our patients aged 20-29 in our cohort, 76% of patients were diagnosed with stage 4 lung cancer compared to only 40% of patients aged 70-79. So you can see that with increasing age the percentage of patients diagnosed with stage 4 lung cancer decreases. It’s extremely high among your younger ages, aged less than 50.
The next thing we looked at was over time has there been a shift to earlier stages of lung cancer identified? So we looked at within each age group in 2010 versus 2018 was there a decrease in the percentage of lung cancers diagnosed at stage 4. What we found was that among our 20-29 year olds, 30-39 year olds and 40-49 year olds there was not a decrease in the percentage of stage 4 disease diagnosed. So most patients continued to be diagnosed with stage 4 lung cancer. Whereas in your older age groups, your age 50-59, 60-69 and 70-79 there was a significant decrease in the proportion of lung cancers diagnosed at stage 4. This is likely due to a number of factors why you see a decrease in the percentage of stage 4 among your older patients but one of them is likely the onset of lung cancer screening during the time period.
So we need to focus on how can we better identify young individuals at high risk for lung cancer because right now in the United States under the most recent guidelines lung cancer screening is recommended for people aged 50-80 who have a 20-pack-year smoking history or greater and who either currently smoke or have quit smoking within the past 15 years. But what we now understand is that lung cancer diagnosed among younger people is quite different compared to lung cancer diagnosed among older people so we really need to focus on figuring out how can we identify those people at high risk for lung cancer so that we can then offer them screening. There are a number of things like risk prediction models, identifying biomarkers that we can use to better select these individuals. But it’s a really complicated problem and it’s something that really we need to focus more on.
The thing we were excited about our study was that it’s not a problem that a lot of people are aware of and so when people think of lung cancer they often think of older individuals diagnosed with lung cancer. So it’s important to know that there is this subset of patients who are diagnosed with lung cancer and currently are diagnosed at a very late stage. Although being young, they still have poor overall survival. So we do need research to better understand how we can improve early detection among this cohort of patients.
