Blood Test Plus Risk Model May Predict Who May Benefit From Lung Cancer Screening

SUMMARY: The American Cancer Society estimates that for 2022, about 236,740 new cases of lung cancer will be diagnosed and 135,360 patients will die of the disease. Lung cancer is the leading cause of cancer-related mortality in the United States. Non-Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers and Adenocarcinoma now is the most frequent histologic subtype of lung cancer.

In the National Lung Screening Trial (NLST) with Low Dose CT (LDCT) screening for lung cancer, there was a 20% reduction in mortality. Following the publication of the results of NLST, and NCCN issued guideline in 2011, the United States Preventive Services Task Force (USPSTF) recommended Lung Cancer screening with Low Dose CT scan in high risk patients. CMS in 2015 determined that there was sufficient evidence to reimburse for this preventive service. The USPSTF expanded the criteria for Lung Cancer screening in 2021 and recommended annual screening with Low-Dose CT for adults aged 50 to 80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years. The new USPSTF 2021 criteria were given a B recommendation, as there was additional research needed, to improve uptake of LDCT screening and to develop biomarkers to more accurately identify individuals, who would benefit from screening.

The authors in a previously published study identified the precursor form of Surfactant Protein B (Pro-SFTPB) as predictive of Lung Cancer risk. They were also able to, in a proof-of-principle study, demonstrate that a four Marker Protein panel (4MP) consisting of Pro-SFTPB, Cancer Antigen 125, CarcinoEmbryonic Antigen, and Cytokeratin-19 fragment, has the potential to identify individuals at risk for developing Lung Cancer, better than Pro-SFTPB alone.

The purpose of this study was to determine whether a blood-based four Marker Protein biomarker panel together with the PLCOm2012 Lung Cancer prediction model would better identify individuals for Lung Cancer screening, compared with current US Preventive Services Task Force (USPSTF) criteria.

The PLCO Cancer Screening Trial was a randomized multicenter trial which evaluated the impact of screening for Prostate, Lung, Colorectal, and Ovarian cancer, on disease-specific mortality. In this study, a biorepository was created for blood specimens that were annually collected, after obtaining consent from the intervention group participants. In this study there were 42,450 individuals in the intervention group who have ever smoked, and 85% of the participants in this intervention arm had at least one blood specimen collection. Individuals with histologically-confirmed lung cancers from the ever-smoked participants in the intervention group, who were diagnosed within 6 years of study entry, and with pre-diagnostic blood specimen available (N= 552), were included in the current study.

Non cancer participants who have ever smoked (N=2193) were randomized 4:1 with lung cancer diagnosed cases and were followed for an additional 13 years during which time they remained cancer-free. For each selected participant, all blood samples collected within 6 years of study entry, or up to the time of diagnosis for lung cancer cases, were included in the study specimen set (N=10,008 blood specimens). The mean age of the study population was 65 years, and 64% were male, 60% were former smokers and 40% were current smokers. The baseline information for the PLCOm2012 model included age, race or ethnic group, education, Body Mass Index, Chronic Obstructive Pulmonary Disease, personal history of cancer, family history of lung cancer and smoking status (current versus former), intensity, duration, and quit time. Levels of the 4 marker proteins in the serum were determined using bead-based immunoassays and biomarker scores were calculated for the combined 4 marker proteins. The researchers assessed the performance of the 4 marker protein panel in combination with the PLCOm2012 lung cancer prediction model, and compared the combination with current USPSTF lung cancer screening criteria, among pre-diagnosis lung cancer, and non-lung cancer serum samples, from the PLCO Cancer Screening Trial.

Using prediagnostic case, and non-case serum samples from the PLCO Cancer Screening Trial data, a combined four-marker protein panel along with PLCO m2012 model showed statistically significant improvement in sensitivity by 11.9% and 9.9% and specificity by 12.9% and 6.9% ,compared with USPSTF 2013 and the recent USPSTF 2021 criteria, respectively. If the 4MP along with PLCOm2012 model was applied to individuals with 10 or more pack-year smoking history, the improved performance of this combination would have resulted in referral to screening of 12.6% more lung cancer cases among the 119 cases who would otherwise receive a lung cancer diagnosis within a year, as well as nonreferral of 29.6% of the 14,061 non-cases. When compared with the USPSTF 2021 criteria, the 4MP plus PLCOm2012 model would have identified for annual screening 9.2% more lung cancer cases and would have reduced referral by 13.7% among non-cases, compared with USPSTF 2021 criteria.

It was concluded that the 4MP plus PLCOm2012 model yielded superior predictive performance and sensitivity and specificity for ruling individuals into LDCT screening, compared with USPSTF 2013 or USPSTF 2021 eligibility criteria, and with the PLCOm2012 model alone. The authors added that the public health benefit is significant, as it better identifies individuals at high risk of lung cancer and expands upon the number of individuals who would be considered eligible for lung cancer screening, thereby addressing some of the limitations of current screening eligibility criteria. These findings have important implications for improving lung cancer screening programs and reducing the burden of lung cancer through personalized risk assessment.

Blood-Based Biomarker Panel for Personalized Lung Cancer Risk Assessment. Fahrmann JF, Marsh T, Irajizad E, et al. J Clin Oncol. Published online January 7, 2022. doi:10.1200/JCO.21.01460.