Current lung cancer screening methods are invasive and inaccessible, with only at-risk patients currently being offered screening Now, in a recent study, researchers have found a new way to use cell-free DNA found in peripheral blood to detect lung cancer. This genome-wide fragmentation method has the ability to separate cancerous patients from non-cancerous individuals to improve cancer screening methods.
Background: Lung Cancer
The current survival rates for lung cancer patients are extremely low, with less than 20% of patients surviving beyond five years after diagnosis. In addition, survival rates are often lower when the cancer is discovered during the late stages of progression (when treatments are less effective). With rising incidences of lung cancer globally, there is an apparent unmet clinical need for improved cancer screening for both high-risk individuals and the general population.
Current Screening Methods for High-Risk Individuals
Current lung cancer screening methods include low-dose computed tomography (LDCT) on the chest. LDCT creates a 3D image inside the body to view tissues and organs. LDCT is underutilised due to its potentially harmful effects from false-positive imaging results and radiation exposure. Currently, this screening service is only offered to at-risk individuals, with less than 6% of at-risk individuals actually screened. At-risk individuals typically consist of individuals aged 50-80 with a smoking history of 20 or more years.
Biomarker development for early detection of lung cancer has a wide range of applications in cancer screening. For instance, biomarkers can (1) distinguish cancer from non-cancerous pulmonary nodes on chest images, (2) investigate proteins levels and (3) evaluate gene expression profiles in the blood. However, results from biomarker levels can be affected by age, inflammation, or other comorbidities such as autoimmune diseases. Currently, no biomarkers have been approved for clinical use during lung cancer diagnosis.
How Liquid Biopsy is Revolutionising Cancer Screening
Due to current challenges, there is an ongoing demand for non-invasive approaches to improve cancer screening for high-risk individuals and the general population. Liquid biopsy has the potential to transform cancer care. Liquid biopsies are able to identify cancer-related features from cell-free DNA (cfDNA) found in peripheral blood. They also have applications relating to non-invasive diagnostics and disease monitoring.
Detection of Lung Cancer Using Cell-Free DNA Fragmentomes
In a recent paper, Mathios et al. developed a genome-wide approach for the analysis of cfDNA fragmentation profiles named DELFI (DNA evaluation of fragments for early interceptions). DELFI has the potential to identify a large number of tumour-derived changes in circulation. DELFI provides a view of cfDNA ‘fragmentomes,’ allowing for the evaluation of the size, distribution, and frequency of millions of naturally occurring cfDNA fragments across the genome. A cfDNA fragmentome comprehensively represents genome and chromatin characteristics.
In the study, researchers examined patient blood samples from 365 individuals examined at Bispeberg Hospital in Copenhagen. The majority (90%) of the 365 individuals were symptomatic, with a high risk of lung cancer. Symptoms included a cough and shortness of breath. The remainder (10%) were asymptomatic at enrollment, with a suspicious lung malignancy found from an x-ray of the chest. Using this method, the researchers detected 121 of the 129 cancerous patients across all stages and subtypes. This included 91% of stage I/II lung cancer cases and 96% of stage III/IV lung cancer cases. DEFLI was also able to distinguish small cell lung cancer from non-small cell lung cancer by looking at the genome-wide fragmentation profiles.
In this study, the researchers presented an improved DEFLI method for genome-wide fragmentation analyses to detect lung cancer. DEFLI is a proposed method that offers a scalable and simple approach to prescreen high-risk individuals for lung cancer. This method shows promise to improve lung cancer detection and reduce the need for follow-up imaging procedures and invasive biopsies. The ability of the DEFLI to separate lung cancer patients from non-cancerous individuals also provides an opportunity to assess both high-risk individuals and the general population.