Lung cancer screening guidelines: Smoking matters, not quitting

Lung cancer screening is a proven method to detect cancers early, resulting in reduced morbidity and mortality. Guidelines regarding lung cancer screening have been published by a few groups, including the American Cancer Society (ACS) who, since 2010, have recommended for low-dose computed tomography screening for those who meet the criteria. One such criterion is years since quitting (YSQ). The 2023 update¹ incorporates significant evolutions that reflect an updated evidence base, in particular related to YSQ. In recognizing that genomic alterations from combustible tobacco exposure do not reliably reverse over time, the guideline update expands the population of those eligible for screening. Furthermore, it serves as a cautionary tale to current episodic smokers regarding the common assumption that quitting smoking removes the risk of lung cancer, particularly with the passage of time.

The rationale for this change is explained as follows: the individual risk of lung cancer does indeed decrease over time once someone quits smoking, but this reduction is relatively lower only if compared with a similar person who continues to smoke. Compared with a person who never smoked, the risk for lung cancer appears to remain three times greater, even at 20 and 30 YSQ. This introduces an entirely new cohort of people now eligible for lung cancer screening, some of whom we may not visualize when imagining the patient who should be contacted for annual screening. For example, picture a business executive in her 50s who previously smoked two packs per day throughout high school and into young adulthood, quitting when she became a parent at age 30 years. She smoked during college and graduate school, but that is now in the distant past. Because of her previous smoking history of 20 pack-years, she is now—for the first time ever—considered a prime candidate for lung cancer screening to reduce the potential morbidity and mortality from lung cancer.

Embedded within this update are acknowledgments of the limitations of available data. For example, large trials used in this analysis did not routinely report on race or ethnicity; and, where race was captured, the vast majority of individuals were White study volunteers. Whether the same eligibility criteria for lung cancer screening applies across races is not clear, but some data suggest that race matters, with lung cancer onset at a younger age among Black people compared to White people, and with a higher proportion of those who did not meet the critical 30 pack-year threshold to initiate lung cancer screening (compared with White people). Finally, how to identify nonsmokers who may benefit from screening is not known. This is important because it accounts for 20% of all diagnoses of lung cancer. We agree that further work into who they are is urgent.

For now, this important update is one that requires swift action at the individual, community, state, and national levels. Since the initial screening recommendation by the American Cancer Society in 2010, uptake of lung cancer screening across eligible populations has been low; in many states, the rate is in the single digits. Because the 2023 update expands the population eligible for screening and notes that smoking of any duration or amount has negative health consequences, the implementation of screening and smoking-cessation programs must accelerate. Furthermore, such programs must embed themselves in communities that particularly face lung cancer disparities, such as in racial minority and rural populations. We know that screening saves lives, and the recent updated guidelines further highlight the crucial need to solve for greater access to screening for all.