Recently the CBC ran an article called, “Blood Test for Early Detection of 8 Cancers Looks Promising.” The article went on to discuss how this promising new blood-based liquid biopsy was able to identify cancers in people.
However, as is typical with new medical advancements, the article requires some further clarification and explanation.
The article described the results of the test like this: “The blood tests found about 70% of eight common types of cancer in the 1,005 patients. The rates varied depending on the type – lower for breast tumours but high for ovarian, liver, and pancreatic ones”.
The author went on to explain that the liquid biopsy test detects mutations in 16 genes tied to cancer. And it also measures eight proteins that are often elevated when cancer is present.
What the Article Gets Wrong About Liquid Biopsies
For starters, liquid biopsy tests that detect tumour DNA have been around for a while. In fact, CTOAM started using these tests almost five years ago!
Secondly, most liquid biopsy tests that detect circulating tumour DNA (ctDNA) are highly accurate, with false negative and positive rates in the 90% plus range.
There is one caveat – you must know the type of mutation you are looking for beforehand, because these tests only detect specific mutations.
The Truth About Liquid Biopsies for Cancer Diagnosis and Testing
In other words, while the BRAF V600M mutation is common in melanoma, just because a person has a BRAF V600M mutation does NOT mean they have melanoma. Similarly, many cases of melanoma do not carry BRAF V600M mutations.
You might be asking, “if you can’t detect unknown cancers with these tests, what are they useful for?”
How Liquid Biopsies for Cancer Really Work
1. Fast and Accurate Results for Diagnosis & Treatment Monitoring
When we sequence the 365 or so genes in a patient’s tumour DNA, we get a list of mutations. If there is a liquid biopsy for any of these mutations, we can use this test to determine if a patient is responding to a treatment. The test will give us the percent of the mutation (i.e. 8%) in the blood. This is reflective to the overall amount of cancer cells in the body.
Then the patient receives the drug. After about a week or ten days, the patient gets re-tested with the liquid biopsy.
If the percent is now at 4-5%, then we know the drug is working. If the percent is the same or higher, we know the drug is not working and we immediately look for a different solution.
What is the important point here?
You do NOT have to wait months to see if the tumour grows or not. This can save your life, as well as a lot of money on treatments that don’t work.
These liquid biopsy tests provide real-time results within a week. They are extremely fast!
See how this works in practice with Damian’s success story. Damian is a CTOAM patient with colon cancer who’s had great success with liquid biopsies, tumour DNA sequencing, and immunotherapy.
2. Fast and Accurate Results for Prevention of Recurrence
If a patient is in remission, then we can do the liquid biopsy to ensure that we catch any new tumours months before they would be large enough to be seen on a CT/MRI or PET/CT. This is when treatments will be most effective.
See Tom’s success story with colon cancer.
3. Liquid Biopsy Prevents Pseudo Progression
While most people have heard of immunotherapy using PD-1 inhibitors, many people do not realize that it can result in something called pseudo progression in about 30% of cases.
This is due to the immune system entering the tumours and killing them. Since the inside of the tumour is very active, it will light up as a positive result using PET/CT.
However, even though the tumours may get bigger and look active under a PET/CT scan, the number of tumours cells will actually be decreasing. So even if the tumour is getting bigger and looks more active using PET scans, it is actually responding to the drugs.
In this case, we would use liquid biopsy to see if the patient has pseudo progression (i.e. lower percentage of ctDNA) or if the immune therapy is not working.
See Betty’s success story with colon cancer to see this in action.
4. Discovers New Gene Mutations
In many cases, tumours have a variety of driver mutations and passenger mutations. Importantly, the drivers and passengers can change roles, creating new treatment resistant populations of tumour cells. There is now a new type of liquid biopsy, called multiplex ctDNA. This test looks at the complete genes and, to date, can cover as many as 90 genes.
A few years back, CTOAM had a patient with an EGFR L858R mutated lung cancer that had, after four years, stopped responding to the anti-EGFR targeted drug, Tarceva. We ran a multiplexed liquid biopsy test and found out they had a new mutation in their EGFR gene called an EGFR T790M. This new mutation had bent the EGFR protein so that Tarceva could not access it.
While the person still had the EGFR L858R mutation, it was only at 0.5% – and the EGFR T790M was at 8%. Therefore, we knew that this new subpopulation of cancers was taking over. We contacted the maker of a new drug that targeted this mutation, called AZD9291. We got the patient on a clinical trial for this drug and the patient immediately started to respond. She is still responding to this day!
See Katherine’s success story with lung cancer.
5. Determines Candidacy for Immunotherapy
Before a person is approved for anti-PD-1 immunotherapy, their doctors will do a test on a biopsy sample to determine if the tumour has PD-1L expression. However, PD-1L expression is transient and different tumours will express it at different times of the disease progression.
As you can imagine, testing a single biopsy sample is a poor way to determine if a patient is a candidate for immunotherapy.
We use a blood-based ctRNA liquid biopsy test that detects the level of PD-1L body-wide and therefore tells us how all of the tumours in the body will respond overall.
See Mark’s success story with carcinoma.
Get the Best Chance of Success with Science!
There is no doubt: liquid biopsies offer cancer patients more accurate and faster diagnosis, treatment monitoring, and prevention of recurrence. These tests save lives, not to mention piles of money that’d otherwise be wasted on ineffective treatments.
Do you want to know whether ctDNA and liquid biopsies can help you get a more accurate and fast cancer diagnosis, treatment, and monitoring? Register for a Precision Second Opinion with our medical team today.
The sooner you reach out, the sooner you’ll know exactly what’s driving your cancer, what your best treatment options are, and how you and your treatment team can access them as fast as possible.
CTOAM is here to help you do all you can for you and your family. Reach out to us anytime with questions or concerns you have about getting the best cancer treatment available, worldwide.
CTOAM, Precision Oncology Specialists: The future of cancer treatment, nowon April 2, 2018
Tags: Immunotherapy, Liquid Biopsy, Success Stories
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