Eligibility criteria for lung cancer screening from the US Preventive Services Task Force (USPSTF) should be broadened, according to the researchers of a recent observational study published in The Lancet Oncology. They recommend lowering the age limit for screening to 50 years and increasing the years of smoking cessation for former smokers.
Issued in 2016, the final USPSTF recommendations call for lung cancer screening in people aged 55–80 years who have a 30 pack-year smoking history. Screening of former smokers is recommending only in those who have quit within the past 15 years.
Yet, according to results from a previous study, almost two-thirds of patients with newly diagnosed lung cancer had not met USPSTF criteria. Further, most patients with lung cancer who had not met USPSTF screening criteria were either long-term quitters (those who had either quit smoking more than 15 years before) or younger (50–54 years) when they received their diagnoses.
“A comparative modelling study based on the USPSTF criteria predicted that an estimated 18,000 lives per year could be saved in the USA if low-dose CT is widely used in the eligible population. However, the Surveillance Epidemiology and End Results Program (SEER) 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 senior author Ping Yang, MD, PhD, consultant, Division of Epidemiology, Department of Health Sciences Research, Mayo Clinic, MN, and colleagues.
In their recent, prospective, observational study, Dr. Yang and her fellow researchers identified 8,739 patients with lung cancer, whom they followed for a median of 6.5 years. They divided patients into those who met USPSTF criteria and those who did not. The latter group was comprised of long-term quitters and younger patients. Dr. Yang and colleagues further divided the USPSTF group into younger (55–69 years) and older subgroups (70–80 years).
The primary outcome of the study was 5-year overall survival, and Dr. Yang and colleagues compared these rates among those who met USPSTF screening criteria with those who did not meet them.
Median overall survival was 16.9 months (95% CI: 16.2–17.5). In long-term quitters, 5-year overall survival was 27% (95% CI: 25% to 30%) compared with 22% in younger smokers (95% CI: 19% to 25%) and 23% (95% CI: 22% to 24%) in those who met USPSTF screening criteria. No significant differences were seen between long-term quitters and those in the USPSTF group, or between those who were younger compared with those in the USPSTF group.
They concluded that patients who had lung cancer but had quit smoking for 15 or more years before their diagnosis and those who were 5 years younger than the age cutoff recommended by the USPSTF for screening had a similar mortality risk as those patients who met all USPSTF criteria.
According to Dr. Yang, the screening for lung cancer according to the USPSTF guidelines is hindered by a high false-positive rate, the potential for overtreatment, and possible hazards from low-dose CT exposure.
“Individuals in both subgroups could benefit from screening, as expansion of USPSTF screening criteria to include these subgroups could enable earlier detection of lung cancer and improved survival outcomes,” wrote Dr. Yang and fellow researchers.
The USPSTF is now in the process of updating these screening recommendations, and considering whether the use of various risk prediction models could improve the risk/benefit ratio of the current recommendations.
According to Christine D. Berg, MD, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, MD—who wrote an accompanying editorial—available risk models include PLCOm2012, LCRAT, LCDRAT, and the Bach models—and all have shown “better utility” than the USPSTF criteria. She noted, however, that implementing these risk models may be a challenge.
Nevertheless, Dr. Berg acknowledged that many lung cancers develop in those who do not meet these guideline criteria.
“Luo [Yang] and colleagues have provided additional information for tackling an important public health problem—lung cancer is the leading cause of deaths from cancer globally. The lung cancer screening community needs to improve selection of individuals into screening programmes and, most importantly, the uptake of screening by those who are most likely to benefit,” concluded Dr. Berg.
This study was funded by the National Institutes of Health, the Mayo Clinic Foundation, the National Institute on Aging, and Taipei Veterans General Hospital-National Yang-Ming University Excellent Physician Scientists Cultivation Program.