Current LDCT lung cancer screening thresholds may be leaving Black patients behind

Chicago healthcare experts are expressing concern that current lung cancer screening guidelines may be leaving some Black patients behind.

This population has historically been underrepresented in LCS trials, despite having a higher incidence of the disease and worse outcomes than their white counterparts. Amid fears that 30-cigarettes-per-day thresholds may be leaving some individuals behind, Cook County Health decided to take a closer look at the numbers.

Analyzing data from 784 patients treated over two years, they found that a 30-pack-year history was not predictive of lung cancer diagnosis, researchers reported Wednesday in JACR. In fact, patients who reported smoking less than 30 cigarettes a day had a similar lung cancer incidence (2.7%) when compared to those reporting smoking histories higher than that mark (2.2%).

“These data raise concern and corroborate prior hypotheses that a smoking threshold of 30 pack-years may not be the most appropriate threshold for screening African Americans,” Anupam Basu MD, with the Department of Radiology at Cook County Health, and colleagues reported Sept. 16.

This pack-year limit was established by the National Lung Cancer Screening Trial—the first randomized analysis to demonstrate lives saved from low-dose CT lung cancer screening. And yet, only 4% of patients in the trial were Black. To test whether these guidelines make sense in practice, the team retrospectively reviewed patients who received a CT lung cancer screening at their large, urban public hospital between 2017 and 2019. Referring providers reported that all in the study population had 30-pack-year smoking histories, while the team gleaned further information from patient intake forms.

All told, 784 patients met the inclusion criteria, having reported sufficient smoking data to calculate pack years. Most were male (57.5%) and Black (66.2%) with a median baseline age of 62. Median total years smoked was 40, with a pack-year median of 25.

Race was not associated with lung cancer diagnosis, the team found. However, Black patients were the only race to have lung cancer if their pack-year habit was less than 30. Basu and colleagues also found “significant” discrepancies between self-reported smoking habits and actual behaviors. While the majority of patients had a pack-year history greater than 30 years, a minority actually met the threshold, reporting that they smoked less than a pack a day.

“Prior data have demonstrated similar discrepancies between smoking histories documented in the medical record and histories obtained during LCS interviews,” the authors wrote. “Although this might imply that providers misunderstand pack-year calculation, we hypothesize that providers are often limited on time during encounters and may simply query duration of smoking, assuming an average of one pack per day. Patients may also misunderstand smoking history questions depending upon phrasing or context. Further study and quality improvement are clearly needed to ensure that smoking histories are accurate for patients undergoing LCS.”

You can read much more on the analysis in the Journal of the American College of Radiology here.