Researchers have found a simple blood test that may be able to diagnose certain solid cancers, monitor the amount of cancer in a patient’s blood, as well as their responses to treatment.
Imagine this scenario: a blood sample is used to diagnose certain
kinds of solid cancers. It can also monitor the amount of cancer in a
patient’s body, and even one’s responses to treatment. Now, researchers
at Stanford University School of Medicine have found a way to turn this scenario into reality.
versions of the approach, which rely on monitoring levels of tumor DNA
circulating in the blood, have required cumbersome and tedious steps to
customize it to each patient. They also have not been sensitive enough.
The researchers’ new approach, published in a paper in Nature Medicine,
is very specific and sensitive and it is expected to be broadly
applicable to many types of cancers. In fact, the researchers accurately
identified about 50 percent of people in the study with stage-1 lung
cancer and all patients whose cancers were more advanced.
researchers’ technique, which they named CAPP-Seq, for Cancer
Personalized Profiling by deep Sequencing, is so sensitive that it can
detect just one molecule of tumor DNA in a sea of 10,000 healthy DNA
molecules in the blood.
Screening Healthy People
the researchers concentrated on patients with non-small-cell lung
cancer (which includes most lung cancers, including adenocarcinomas,
squamous cell carcinoma and large cell carcinoma), the approach is
expected to be broadly applicable to many different solid tumors
throughout the body.
According to the paper, it is also
conceivable that it could be used to track the progress of a previously
diagnosed patient, as well as to screen healthy or at-risk populations.
Maximilian Diehn, Ph.D., an assistant professor of radiation oncology
at Stanford, told Healthline, “The blood test that we have developed for
lung cancer could be adapted to nearly any cancer. We are starting to
work on establishing it in the clinical lab here at
Stanford…Currently, after a patient completes standard treatment for
cancer it is often difficult to tell if all of the cancer cells have
been eliminated. Patients therefore need to be followed with repeated
scans. We’re hopeful that our blood test will help to identify patients
who still have cancer left in their bodies at the end of treatment. If
so, it is possible that those patients could receive more treatment and
increase their chances for a cure.”
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Liquid Biopsy for Lung Cancer
speaking to Healthline, Dr. Ash Alizadeh, a hematologist and oncologist
who was also involved in the study, agreed with Diehn. “One of the most
difficult things we struggle with, is how advanced the diseases of our
patients are when they show up to see us and when we are seeing these
patients for treatment, how long it takes before we are able to
determine if they are having a response to the treatment.”
continued, “The idea for this test is to get access to the tumor
through the blood, relatively noninvasively compared to doing a biopsy.
The current study focuses on taking solid tumors, which is the majority
of cancer, and transforming them to liquid tumors by looking at what all
cells do, which is why they die to release their DNA. We look in the
blood for evidence of that DNA as a magnifying glass for what’s going on
in the tumor.”
Emphasizing that the test is a liquid biopsy for
lung cancer, which enables one to measure the presence or absence of
lung cancer as well as the amount of lung cancer, and to monitor for it
very accurately, Alizadeh said, “It’s relatively inexpensive, and it
doesn’t involve getting scans. We see pretty striking results very early
during the course of treatment. We are now starting to monitor it for
lymphomas, cancer of the esophagus, pancreas, breast, and colon cancer.”
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Each Cancer Is Genetically Different
that each cancer tends to be genetically different for different
patients, Alizadeh said that although sets of mutations can be shared
among patients with a given cancer, the researchers looked for which
genes are most commonly altered, and used computational approaches to
identify the genetic architecture of the cancer. That allowed us to
identify the part of the genome that would be best to identify and track
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expect CAPP-Seq to also serve as a prognostic tool. The technique
detected small levels of circulating tumor DNA in one patient who was
thought to have been successfully treated for the disease. However, that
patient experienced disease recurrence and died.
The researchers are designing clinical trials to see if CAPP-Seq can improve patient outcomes and decrease costs.