Should Screening Criteria for Lung Cancer Be Expanded?

Lung cancer patients who fall outside the US Preventive Services Task Force (USPSTF) guidelines for screening have similar mortality rates to those who did qualify for screening, according to a new analysis published in the Lancet Oncology.

The USPSTF guidelines recommend screening for lung cancer using low-dose computed tomography (CT) for individuals age 55 to 80 years, with a smoking history of at least 30 pack-years, and either currently smoke or quit within the past 15 years.

The analysis also found individuals who quit smoking more than 15 years earlier and those younger than 55 years may also benefit from inclusion in screening criteria.

“The Surveillance, Epidemiology, and End Results Program database as well as data from two other independent cohorts have shown that only a third of patients diagnosed with lung cancer in the USA meet the USPSTF screening criteria, suggesting that many potentially high-risk individuals are not eligible for low-dose CT screening,” wrote study authors led by Yung-Hung Luo, MD, of the Mayo Clinic in Rochester, Minnesota.

The new study examined whether patients who quit smoking 15 to 30 years earlier (long-term quitters) and patients age 50 to 54 years at the time of lung cancer diagnosis have a higher risk of death than those fitting the USPSTF guidelines.

The study drew from two cohorts: a hospital cohort at the Mayo Clinic, and a community cohort from Olmsted County, Minnesota. It included a total of 8,739 patients with lung cancer, followed for a median of 6.5 years. The median overall survival in the full cohort was 16.9 months.

The cohort was divided into a control group that met the USPSTF screening criteria (5,869 patients), a long-term quitter group (1,299 patients), and a younger group (630 patients). The 5-year overall survival (OS) rate was 27% in long-term quitters, 22% in the younger patients, and 23% in the USPSTF group.

On a multivariate analysis, the 5-year OS rate was no different between long-term quitters and USPSTF patients in the hospital cohort, with a hazard ratio (HR) of 1.02 (95% CI, 0.94–1.10; P = .73). The same was true in the community cohort, with an HR of 0.97 (95% CI, 0.75–1.26; P = .82). A matched analysis yielded similar results.

The 5-year OS rate was also no different between younger patients and the USPSTF group; in the hospital cohort, the HR was 1.16 (95% CI, 0.98–1.38; P = .08); in the community cohort, the HR was 1.16 (95% CI, 0.74–1.82; P = .52).

“Our results show a higher frequency of early-stage lung cancer among long-term quitters than among the USPSTF group in the hospital and community cohorts,” the authors wrote. “Therefore, in terms of tumour stage, long-term quitters might have a higher survival benefit from screening than those who quit within the past 15 years, as a result of greater detection of early-stage lung cancer.”

In an accompanying editorial, Christine D. Berg, MD, of the National Cancer Institute in Bethesda, Maryland, noted that the USPSTF is currently in the process of updating its lung cancer screening recommendations.

“The panel is considering whether risk prediction models will improve the balance of benefits and harms compared with existing recommendations,” she wrote.

An individualized risk-based modelling approach could be adopted, but it carries challenges in implementation.

“Luo and colleagues have provided additional information for tackling an important public health problem-lung cancer is the leading cause of deaths from cancer globally,” Berg wrote. “The lung cancer screening community needs to improve selection of individuals into screening programs and, most importantly, the uptake of screening by those who are most likely to benefit.”