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Providers > Standards of Care
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Standards of Care
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Current standards of care
The diagnostic tools most commonly used to detect and localize lung cancer
are sputum cytology, bronchoscopy, x-ray, and
computed tomography (CT). There is no single standard of care for
early lung cancer screening, but CT scans are gaining momentum as the
detection method of choice.
With advances in resolution, CT can now detect nodules in the lung as small
as 1mm. This makes CT a very sensitive tool for the detection of lung cancer,
but as the resolution of CT scanners has increased so has the fraction of
patients found to have suspicious nodules. This suggests that there is a
specificity problem with CT, leading to a high rate of false positive results
(low specificity). Typically, 95% of nodules found by screening CT are
eventually determined to be benign.(3)
LungSign™ — a compliment to CT
LungSign™ is a complimentary approach to patient diagnostic management.
There are two distinct ways in which LungSign supports CT: (1) by providing
a measure of malignancy that can expidite diagnosis and reduce the need for
repeat CT scanning; and (2) as a test before CT scanning.
According to recent publications, most high-risk individuals who undergo CT
will be found to have pulmonary nodules, but 92-96%(3)
of those nodules will prove to be
benign. On a diagnostic track that can require two years to conclude,
patients with positive scans accrue additional costs, radiation exposure and
increased anxiety. A negative LungSign™ test result can reassure
patients during the period where nodule growth is being assessed. On the other
hand, a positive LungSign™ test result can provide biological evidence
of malignancy in support of a nodule-positive CT scan result, and contribute
to a more rapid evaluation.
LungSign™ — before CT
LungSign™'s second role is as a pre-CT test. This provides an opportunity
to identify a very high risk group for CT and diagnostic follow-up to avoid cost
and radiation exposure, particularly among patient groups with whom radiation
should be limited — lung cancer survivors; patients exposed to other
radiology-based screening methods (e.g., mammography). LungSign™ also helps
to indicate the presence of bronchial cancers, which would otherwise be missed
during CT alone.
Lung Cancer detection methodologies: further discussion
1. Sputum cytology:
one of the oldest approaches to detecting lung cancer, sputum cytology relies on
finding cancerous cells in the fluids brought up from the lungs. Sputum cytology
is not widely used for early detection due to its low sensitivity, since malignant
cells are usually not found in the sputum specimens of patients with early
lung cancer.
2. Bronchoscopy:
although bronchoscopy does allow direct observation of the large airways, it has
limited ability to visualize the lung's periphery, where approximately 40% of all
lung cancers occur. Furthermore, the invasiveness and expense of bronchoscopy
limit its use as a detection tool.
3. X-ray:
X-ray technology has been a much-used lung cancer detection method for many
years. However, x-rays do not identify tumors smaller than 2cm, limiting
their usefullness for early detection. X-rays also generate a high number
of false positive readings, since other pulmonary conditions, such as
infections, TB and sarcoidosis, produce radiographs with similar appearance
to lung cancer.
4. CT Scans:
Computed Tomography (CT) is emerging as a powerful tool for the detection of
lung cancer. Unfortunately, CT scans alone can often not distinguish
between benign and malignant nodules.
In the ongoing US National Lung Screening Trial (NLIST), which utilizes CT as
a method of early lung cancer screening, most volunteers have been fount to have
suspicious nodules that require follow up. Follow up typically consists of a
higher-dose, diagnostic CT scan, repeat scanning after a period of three to six
months, fine needle aspiration or biopsy. It can take up to two years, and as
many as nine CT scans, to establish a diagnosis.
In addition to its high rate of false positives, some physicians worry about
the effect of CT radiation exposure. Low dose CT scans subject patients to a
radiation dose equivalent to 50-100 chest x-rays. (4)
While the risk to an individual is
statistically small, the effect on the general population could become
significant as CT scans grow in popularity.
Given the aggressive nature of lung cancer, concerns about radiation-induced
malignancy are often secondary to a need for diagnosis. In consequence, CT
is fast becoming the dominant approach for lung cancer detection.
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Perceptronix is a cancer diagnostic service company focused on detecting cancer
at early stages to improve patient outcomes.
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