By Christian Rolfo, MD, PhD, MBA, Dr.hc.
Over the past several years, three large randomized clinical trials demonstrated that low-dose computed tomography (LDCT) screening is a valuable method for lung cancer screening in high-risk individuals and can significantly reduce lung cancer mortality.1-3 Economic costs, technical and organizational requirements, exposure to not negligible radiation doses, the risk of false-positive results and the subsequent need for unnecessary invasive procedures are some of the obstacles to a broader clinical implementation of LDCT screening. The use of minimally invasive biomarkers that can discriminate between patients with lung cancer and healthy individuals might increase the adherence to the LDCT screening, which is quite low even in countries where it is reimbursed and approved, thereby resulting in a better selection of individual candidates for the screening, as well as reduced false-positive cases and increased cancer detection.
Different liquid biopsy (LB) approaches have been studied to date, ranging from microRNAs panels,4-5 metabolomics analyses,6 and circulating tumor DNA (ctDNA). Several studies have evaluated the role of ctDNA for early lung cancer detection. However, the estimated clonal mutant allele frequency (MAF) in ctDNA of potentially curable lung cancers, such as T1a-b, is quite low and usually under the limit of detection of most of the LB tests used so far.7 Furthermore, the presence of non-tumor derived mutations due to clonal hematopoiesis (CH) might represent a further obstacle for the clinical implementation of ctDNA as biomarker for early lung cancer diagnosis.8 Recently, a renewed interest in this biomarker has emerged with the publication of the results of some promising studies evaluating the use of ctDNA with different approaches. Chabbon et al.9 reported the results of the Lung-CLiP (lung cancer likelihood in plasma) study, using an optimized CAPP-Seq (CAncer Personalized Profiling by deep Sequencing) protocol. Interestingly, they reported that tumor-derived mutations and those of CH origin have different fragment size and mutational signature, suggesting that these features could be useful to prevent false-positive results in healthy individuals. Furthermore, baseline ctDNA levels before surgery were a strong prognostic factor, likely reflecting the presence of occult micrometastases, suggesting a potential role of ctDNA analysis not only for early lung cancer detection but also for minimal residual disease monitoring in patients treated with (neo)-adjuvant therapies.
Other studies have focused on blood-based multicancer tests, such as the Circulating Cell-free Genome Atlas (CCGA), which recently evaluated a targeted methylation analysis of circulating free DNA (cfDNA) for cancer detection and localization in more than 15,000 participants. After a discovery phase, a methylation-based classifier was selected and then clinically validated in training set and in an independent validation set. The methylation-based classifier achieved high specificity (false-positive rate < 1%) in more than 50 cancer types, including lung cancer, and predicted the tissue of origin in 96% of samples with a cancer-like signal.10 Further clinical validation of this assay is ongoing (NCT02889978).
The presence of circulating tumor cells (CTCs) has a negative prognostic role in different advanced solid tumors, including lung cancer.11 The prospective, multicenter, French AIR study tested the performance of ISET (isolation by size of epithelial tumor cell technique) as a lung cancer screening tool in individuals eligible for LDCT screening as per National Lung Screening Trial criteria and who have chronic obstructive pulmonary disease. Unfortunately, the ISET Rarecells test used in this study had too low a sensitivity (at baseline, the sensitivity of CTC detection for lung cancer detection was 26.3%) to be used as a reliable lung cancer screening tool for patients at high risk.12
Collectively, the results of these studies showed a potential role for different LB approaches. However, it is likely that these tests would not have sufficient sensitivity and specificity for being used as screening method alone. Combinatorial approaches between different LB tests and/or with radiographic methods and rigorous study design would be the key for success.
About the author: Dr. Rolfo is is the director of the Thoracic Medical Oncology and the Early Clinical Trials at the University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center (UMGCCC). He is also a co-chair for the IASLC Hot Topic: Liquid Biopsy meeting, to be held October 2-3, 2020.
- National Lung Screening Trial Research Team; Church TR, Black WC, Aberle DR, et al. Results of initial low-dose computed tomographic screening for lung cancer. N Engl J Med. 2013;368(21):1980-1991.
- de Koning HJ, van der Aalst CM, de Jong PA, et al. Reduced Lung-Cancer Mortality with Volume CT Screening in a Randomized Trial. N Engl J Med. 2020;382(6):503-513.
- Pastorino U, Silva M, Sestini S, et al. Prolonged lung cancerr screening reduced 10-year mortality in the MILD trial: new confirmation of lung cancer screening efficacy. Ann Oncol. 2019;30(7):1162-1169.
- Sozzi G, Boeri M, Rossi M, et al. Clinical utility of a plasma-based miRNA signature classifier within computed tomography lung cancer screening: a correlative MILD trial study. J Clin Oncol. 2014;32(8):763-773.
- Montani F, Marzi MJ, Dezi F, et al. miR-Test: a blood test for lung cancer early detection. J Natl Cancer Inst. 2015;107(6):djv063. Print 2015 Jun.
- Zhang L, Zhu B, Zeng Y, et al. Clinical lipidomics in understanding of lung cancer: Opportunity and challenge. Cancer Lett. 2020;470:75-83.
- Abbosh C, Birkbak NJ, Swanton C. Early stage NSCLC — challenges to implementing ctDNA-based screening and MRD detection. Nat Rev Clin Oncol. 2018;15(9):577-586.
- Russo A, De Miguel Perez D, Gunasekaran M, et al. Liquid biopsy tracking of lung tumor evolutions over time. Expert Rev Mol Diagn. 2019;19(12):1099-1108.
- Chabon JJ, Hamilton EG, Kurtz DM, et al. Integrating genomic features for non-invasive early lung cancer detection. Nature. 2020;580(7802):245-251.
- Liu MC, Oxnard GR, Klein EA, et al. Sensitive and specific multi-cancer detection and localization using methylation signatures in cell-free DNA. Ann Oncol. 2020;31:745–759.
- Krebs MG, Sloane R, Priest L, et al. Evaluation and prognostic significance of circulating tumor cells in patients with non-small-cell lung cancer. J Clin Oncol. 2011;29(12):1556-1563.
- Marquette CH, Boutros J, Benzaquen J, et al. Circulating tumour cells as a otential biomarker for lung cancer screening: a prospective cohort study. Lancet Respir Med. 2020;8(7)709-716.