Alexandra Potter Discusses Health Disparities in Lung Cancer Screening, Treatment

New research shows that adopting a 20-year smoking duration cutoff instead of a 20-pack-year cutoff to determine eligibility for lung cancer screening significantly improves the proportion of patients with lung cancer who are eligible for screening and eliminates racial disparities in screening eligibility.

To discuss these findings, Lung Cancers Today spoke with Alexandra Potter, Program Director of the American Lung Cancer Screening Initiative. Ms. Potter spoke in depth about the disparities that exist in lung cancer screening and treatment, factors that drive these disparities, and what can be done to help.

About Ms. Alexandra Potter:

So, I’m the President of the American Lung Cancer Screening Initiative, a national 501(c)(3) nonprofit focused on increasing awareness of lung cancer screening. And then I’m also a Research Coordinator at Massachusetts General Hospital.

Talk to us about the racial disparities that exist in lung cancer screening and treatment. What are some drivers of these disparities?

Yeah, so there is a number of disparities. Broadly speaking, in the United States, Black men have the highest lung cancer incidence of any racial or ethnic group. Black men and women tend to be diagnosed at more advanced stages when compared to white men and women, and they tend to have worse survival compared to white men and women. So, that’s looking at incidence, the stage of lung cancer diagnosed, and the survival of patients diagnosed with lung cancer.

The other thing is, when you look at, of patients with lung cancer who would have qualified for lung cancer screening and would’ve had the opportunity to be screened for lung cancer, there’s a disparity in the proportion that would’ve qualified.

So, I can pull up the exact numbers, but in our study we looked at, of patients in the Southern community, I guess, broadly speaking, there’s been a lot of literature that has shown that a lower proportion of Black individuals with lung cancer would have met the current United States Preventive Services Task Force lung cancer screening eligibility criteria. And the reason that’s important is that eligibility for lung cancer screening is a … Being ineligible for lung cancer screening is a barrier to having insurance coverage for screening and, therefore, a barrier to early detection

And so, any disparity we see in terms of lung cancer screening eligibility will likely contribute to further disparities down the line, so continue to widen disparities in the stage of lung cancer diagnosed and survival.

How is pack-year smoking history measured, and is it a reliable measurement for lung cancer risk?

So, the smoking pack-year, it’s the number of years someone has smoked, multiplied by the number of packs per day on average that they’ve smoked. So, there’s 20 cigarettes in a pack. So, for example, if someone smoked 20 cigarettes per day, you do 20 divided by 20. That’s one pack of cigarettes per day, multiplied by the number of years they’ve smoked. It’s a measure of cumulative tobacco exposure that tries to account for both how long someone has smoked and how intensely or how many cigarettes per day they’ve smoked.

But as we had noted in our studies, there’s several issues with using pack-year smoking history. The first is that someone’s recount of the average number of cigarettes they’ve smoked every day, for every day they’ve smoked in their entire history, is very inaccurate. It varies a lot. So, how much someone smoked when they were 20 is a lot different than how much someone smoked when they were 50.

And so, we help a lot of people get screened, and sometimes we’ll ask them, “How many cigarettes per day do you smoke?” And they’ll say, “Seven.” But then when you ask them how many cigarettes per day they smoked when they were 30, it might have been 20. And so, if you were to use. That’s a huge difference, and it has a huge difference on their pack-year smoking history.

So, there’s that bias, in terms of recollection and how accurate that recollection is of how intensely someone has smoked.

The other bias is that a lot of literature has shown that smoking duration is more strongly associated with lung cancer risk when compared to smoking intensity. But the issue with the pack-year is it actually attributes equal weight to smoking duration and smoking intensity, even though they’re not equal.

And so, what happens is, for people who have smoked less intensity or fewer cigarettes per day, the pack-year actually underestimates their lung cancer risk. And people who smoke less intensely tend to be individuals from racial and ethnic minority groups. And so, because of that, the pack-year likely underestimates lung cancer risk among racial and ethnic minority groups.

Talk to us about the study you led. How was it conducted, and what were the findings?

So, our study looked at two prospective cohorts. We looked at the Southern Community Cohort Study, which is a prospective cohort of over 80,000 high-risk men and women, predominantly Black and white men and women from 12 Southeastern US states. That was the first cohort we analyzed.

The second cohort we analyzed was the Black Women’s Health Study, which is a prospective cohort of over 50,000 Black women from predominantly metropolitan areas in the US. And so, what we did was we looked first at, in these two cohorts of people diagnosed with lung cancer, what proportion would have qualified under the current lung cancer screening recommendation by the United States Preventive Services Task Force.

So this recommendation, it’s called the 2021 USPSTF recommendation, and it requires people to be between the ages of 50 and 80, have at least a 20 pack-year smoking history, and either currently smoke or quit smoking within the past 15 years. So those are the criteria to be eligible.

And what we found was that, of Black people in the Southern Community Cohort Study diagnosed with lung cancer, only about 57% would have qualified for lung cancer screening under that guideline. And that was considerably lower compared to … I have to pull it up, but considerably lower compared to the proportion of white people in the Southern Community Cohort Study with lung cancer who would have qualified. So that was 74%.

So, it’s about 57.6% of Black lung cancer patients would’ve qualified for screening, compared to 74% of white lung cancer patients. So that’s a really notable disparity in screening eligibility under the current guideline, which was supposed to, actually … It’s going back into history a little bit. The 2021 USPSTF guideline had been revised from the original guideline to lower the pack-year smoking industry and lower the age bound, in an attempt to reduce racial disparities.

So, the fact that you still see that large of a disparity in lung cancer screening eligibility means that those changes that had been made were not completely effective in eliminating disparities

The other thing was we looked in the Black Women’s Health Study at the proportion of Black women with lung cancer who would have qualified, and only 42.5% of Black women with lung cancer would have met the original, the 2021 USPSTF lung cancer screening eligibility criteria.

And so, that was the first thing we did. We then asked ourselves, “What’s causing this disparity in lung cancer screening eligibility?” And the primary factor causing that disparity was the 20 pack-year cutoff, where a lot of Black lung cancer patients had smoked 16, 17, 18, 19 pack-years, but were not crossing that 20 pack-year threshold.

And so, our next question was, “Why do Black patients tend to have a lower pack-year smoking history compared to white patients with lung cancer?”

And so, we looked specifically at the two components that make up pack-year smoking history, smoking intensity and smoking duration. And we compared those between Black lung cancer patients and white lung cancer patients. And we found that the Black and white lung cancer patients, they actually tend to smoke a similar number of years at lung cancer diagnosis.

So, Black lung cancer patients smoked about 43 years, whereas white lung cancer patients smoked about 45 years. So, a little bit lower among Black lung cancer patients, but roughly very similar.

But the biggest difference was in smoking intensity, where Black lung cancer patients were only smoking a median of 12 cigarettes per day, compared to 20 cigarettes among white lung cancer patients.

And so, it’s really the difference in smoking intensity that was causing the difference in pack-year smoking history, which was causing the difference in lung cancer screening eligibility.

So we then asked ourselves, “What if we just removed this whole concept of intensity from the lung cancer screening guideline and only used a duration cutoff as opposed to a pack-year cutoff?”

And so, what we did was we looked at eligibility under the USPSTF guideline and compared that to a proposed guideline that replaces the 20 pack-year requirement with a 20-year smoking duration requirement. So, completely removing intensity in the equation.

And what we found was that, when using this proposed guideline with a 20-year smoking duration cut-off instead of a pack-year cutoff, the percentage of Black lung cancer patients that would’ve qualified increased from 57.6% to 85.3%. And the percentage of white lung cancer patients that would’ve qualified increased from 74% to 82%.

And notably, the racial disparity in lung cancer screening eligibility was completely eliminated when using duration instead of pack years to select people for lung cancer screening.

We also found that, in the Black Women’s Health Study, the 20-year duration cutoff, instead of the pack-year cutoff, increased the proportion of Black women who would’ve qualified from 42.5% to 63.8%. So, really notable increase as well in both cohorts.

And so, from that, we concluded that transitioning to using a 20-year smoking duration cutoff, instead of a 20 pack-year cutoff, would, one, improve screening eligibility in all groups evaluated for both Black and white people, but most notably for Black people, and importantly, completely eliminated the racial disparity in lung cancer screening eligibility.

What are the clinical implications of these findings?

So, I think that the USPSDF last changed their lung cancer screening eligibility in 2021, was when the last official recommendation came out. And so, they will be due for a potential revision to their guideline in the coming years.

And I think that, as the USPSTF is considering whether to keep the current guideline or to incorporate new revisions into the guideline, I’m hoping that these findings will be taken into consideration.

And I think that one thing that’s really important, an important goal of defining lung cancer screening, of just screening eligibility criteria in general, is to make sure that the criteria being used are equitable. And so, I’m hoping that the concept of transitioning from using pack-years to duration will be taken into consideration and potentially incorporated into the next revision of the USPSTF guideline.