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Opinion | More people need to be screened for lung cancer

Disposed-of cigarette butts in New York - Lung Cancer
Thought Leader: Leana Wen
November 28, 2023

Lung cancer kills more than 130,000 Americans a year, more than any other cancer. But that number need not be so high. Health officials could significantly reduce the toll of the disease simply by increasing screening for it.

Only about 1 in 4 cases of lung cancer are diagnosed in early stages. Why? A key reason is that the screening rate is abysmally low. According to a report last year from the American Lung Association, less than 6 percent of eligible Americans receive annual low-dose CT scans. In some states, the screening rates are as low as 1 percent.

Updated guidelines from the American Cancer Society (ACS) seek to increase the number of people who qualify for such screenings. Hospitals, insurers and primary-care providers should not delay in implementing these recommendations.

It’s common knowledge that the top risk factor for lung cancer is cigarette smoking, which is linked to 80 to 90 percent of lung cancer deaths. The amount and duration of smoking are reflected as “pack-years,” or the number of packs consumed per day multiplied by the number of years someone smoked. The risk of cancer increases with pack-years as well as age. It decreases for those who quit smoking.

ACS previously recommended annual screenings for 55-to-74-year-olds with at least a 30-pack-year smoking history and who quit smoking less than 15 years ago. The new guidelines made several key changes, including widening the age parameters to between 50 and 80 years, lowering the smoking history to 20 pack-years and eliminating the “years since quitting” metric. (There is insufficient data for people over 80, who are advised to discuss their health status and the merits of continued screening with their physicians.)

The study also demonstrates that expanding eligibility can help mitigate disparities. Research has shown that Black Americans report a lower pack-year history compared with White Americans and are more likely to be diagnosed with lung cancer before age 55. And women report lower pack-year histories than men. Increasing the pool of high-risk people would thus have an outsize impact on women and minorities in terms of who qualifies for screenings.

This new eligibility aligns with that of several other major organizations, including the influential U.S. Preventive Services Task Force, which also recommends starting screening at age 50 for those with a 20-pack-year history. The task force, however, does not recommend screenings for people who quit more than 15 years ago.

Eliminating that last criterion, however, could have even more of an impact than the changes in age or pack-year recommendations. Health officials have long believed that former smokers’ risk of cancer declines over time. But while it is true that the chance of developing lung cancer falls after cessation, the risk remains significantly elevated. At 15 years after quitting, the risk is up to 10 times greater compared with the risk for people who never smoked. Even after 30 years, the risk of dying of lung cancer was still three to four times higher.

Age also plays a role. In a pivotal study published this month in the journal Cancer, researchers found that while there was a decrease in risk in the first five years after quitting smoking, the decline slows, and beyond 10 years after cessation, the increased risk from aging outweighs the effect of quitting. They estimated that removing the “years since quitting” criterion would make an additional 4.9 million people eligible for screening and save an extra 8,275 lives each year.

This change alone could dramatically increase screening. Individuals who have already been doing yearly exams would be encouraged to continue them, instead of stopping 15 years after quitting.

Moreover, the new recommendations are more straightforward. It doesn’t matter whether someone is a current or former smoker; if their pack-years exceed 20 and they are between 50 and 80, they need screening. People who smoked heavily in their teens but stopped many years ago might not consider themselves to be at risk for lung cancer, but they are now eligible and should get annual low-dose CTs.

It’s remarkable that, as of 2021, more than 75 percent of women between 50 and 74 had received a mammogram within the past two years. About 72 percent of people in a similar age group received a colorectal cancer screening in accordance with national guidelines. ACS’s new guidance should prompt a nationwide awareness campaign to drive lung cancer screenings. Just as for other cancers, early diagnosis and prompt treatment are key to saving lives.

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