#LungCancer #EarlyDetection #LiquidBiopsy
#DNAMethylation #Diagnosis #LDCT
Lung cancer remains the leading cause of
cancer-related death worldwide. This high mortality rate is largely due to the
fact that
diagnosis often occurs at an advanced stage, when therapeutic options
are limited and less effective. In this context,
early and reliable screening
is essential to improve patient outcomes.
Currently,
low-dose computed tomography (LDCT)
is the recommended screening method for high-risk populations, particularly
heavy smokers. However, its use is
hindered by several limitations: a high rate
of false positives leading to unnecessary invasive procedures, cumulative
radiation exposure, and significant healthcare costs.
To overcome these challenges, research is
turning to
less invasive and potentially more specific approaches. Among them,
liquid biopsy is generating growing interest. This method is based on the
analysis of circulating tumor DNA (ctDNA) detected in blood, paving the way for
simpler, safer, and potentially earlier screening.
The objective of this study was to evaluate the
diagnostic performance of liquid biopsy in lung cancer screening among
high-risk populations, comparing it with conventional methods such as LDCT.
Can cancer be detected in a drop of blood?
Forty-four studies evaluating methylation
markers of
circulating tumor DNA for lung cancer screening were selected.
Extracted data included sensitivity, specificity, and types of markers used.
The data were aggregated through a meta-analysis adjusted for inter-study
heterogeneity. Subgroup analyses examined the impact of tumor stage,
histological type, and genetic panel composition.
The results revealed a
mixed diagnostic
performance. The
overall sensitivity of the test was relatively modest,
reaching 54%, meaning that about one in two cancer cases goes undetected. On
the other hand,
specificity was high at 86%, reflecting a reliable ability to
correctly identify healthy individuals with a limited false-positive rate.
A more detailed analysis showed that
the test
performed significantly better under certain conditions. It was
more effective
at detecting cancers at an advanced stage, with sensitivity rising to 77%,
compared to 50% for early-stage cancers. The test also showed
superior
effectiveness for small-cell lung cancer compared to non-small-cell lung
cancer. Furthermore,
genetic panels combining several markers performed better
than those relying on a single biomarker.
Among the most frequently studied and promising
genes were RASSF1A, APC, SHOX2, and SOX17, which
appear to play key roles in the diagnostic potential of this approach.
Not yet ready to replace the CT scanner
Lung cancer remains a formidable disease,
primarily because it is often
diagnosed late, when curative options are
limited. Improving
early detection is therefore a major challenge. One of the
main difficulties in screening lies in balancing sensitivity and specificity.
While
LDCT is effective in identifying suspicious lesions, it also generates a
high number of
false positives, leading to
unnecessary invasive examinations.
The goal of this study was to assess to what
extent
methylation tests of circulating tumor DNA could serve as an alternative
or a complement to imaging in lung cancer screening.
The findings confirm that, in their current
form,
these tests cannot replace CT scans due to insufficient sensitivity,
especially for early-stage cancers. Too many cases would go
undetected—precisely when intervention is most beneficial. However,
their high
specificity makes them strong candidates for
complementary use. When used as a
triage tool, these tests could help
refine the interpretation of
imaging-detected anomalies. A negative blood test, for instance, could support
the hypothesis of a false positive on a scan, thereby avoiding costly,
invasive, and stressful procedures for the patient.
This combined strategy could
improve the
benefit-risk balance of screening and enhance its acceptability. Given the
current limitations, further research is needed. To integrate this approach
effectively into clinical practice,
standardization of analysis protocols and
validation of these biomarkers in large-scale, prospective studies targeting
high-risk populations are essential.
These next steps are critical to making liquid
biopsy a true asset in the lung cancer screening arsenal.
Read next: Breathing can kill—even without smoking.
