Startup companies looking to revolutionize the world of cancer screening
By Kathryn E. Vinson, MS, CCRC
I’ve said it before and I’ll say it again, we live in some pretty amazing times. Our ability to diagnose and treat a myriad of diseases, including many cancers, has come light years from where we once were. A hundred years ago, many cancer diagnoses meant massive surgeries, and/or getting severely burnt with radiation. Not being dramatic here – a great-great uncle suffered severe radiation burns in the 1930s.
For most of us, cancer screenings have become routine. We ladies go to the gynecologist every year for our checkups and have our mammograms once we reach 40. The majority of us go in for routine colonoscopies starting at 50. Gentlemen have their prostate checked. Though these tests are intrusive (to say the least) we deal with that unpleasantness knowing that it could literally save our lives.
But what if I were to tell you that there are a few companies out there that are working on much simpler screenings? What if a simple blood test could screen for colorectal cancer? What if a simple blood test could screen for ALL cancers? Many of us would think – no way, that sounds too good to be true. Well, the truth of the matter is that this IS happening, but there are a lot of issues to consider with these tests. With that, let’s take some time today to talk about “liquid biopsies,” what they are, how they work, and what they could realistically mean for you.
What is a liquid biopsy?
Simply put, a liquid biopsy is a blood test that looks for certain markers that can identify types of cancer. For many of these tests that are in the development pipeline, they are looking at DNA markers that show up in the blood when cancer is present. One company, Freenome, is looking specifically at screening for early stage colorectal cancers. Two other companies, Grail and Thrive, are interested in a pan-cancer solution – that is, a test that could identify all (or at least multiple) cancers from one blood test.
So, you’re thinking – hang on – during cancer treatment, doctors already have markers in the blood that they can use to see how my disease has progressed. In many cases, that’s true; however, what these companies are working on is detecting cancer before it gets to the stage that it is producing those high-level markers. These tests would be so sensitive that they could detect DNA fragments in the bloodstream that are thrown off by tumors.
We have seen a similar screening tool that is currently marketed – Cologuard. You’ve probably seen the commercials for this test on TV. It works in a similar way to the liquid biopsies in development by looking for abnormal DNA, only in stool rather than blood samples.
How effective are these tests?
This is where it gets a little tricky. When we talk about tests that are used to diagnose or screen for a certain disease or illness, we talk about sensitivity and specificity. Sensitivity is the ability of a test to identify the presence of a disease when it is actually there (think true positive). Specificity is the opposite – correctly coming up negative when there is no disease.
So, let’s put this into perspective. Per Cologuard’s website, their test found 92% of cancers (that is sensitivity) and was negative in 87% of cases where no cancer was present (specificity) in testing 10,000 people at average risk for colorectal cancer. If you look at it the other way around, 8% of people that did have cancer, had a false negative reading, while 13% of people that did not have cancer, got a false positive. As another comparator that most of us are familiar with, the American Academy of Family Physicians puts the sensitivity of the rapid strep test at anywhere from 90-95%.
When we compare that to the data that Freenome has released – they show 94% sensitivity and specificity. These are some pretty great numbers, but their sample size was 574 – so we need to understand the difference in the “power” of these statistics; however, it should be noted that a study involving 10,000 volunteers is planned for the company’s next study.
With all this information, what is a person to do? Do we stick with the standard screening methods that we are used to, or do we step out into the future with these new screening methods? My honest opinion (and it does not reflect the opinions of Cancer Horizons), is – well, it depends. I am thrilled to my bones for non-invasive screening methods to come to the market. The ease of these tests could mean that so many more people would be willing to get tested. That means early detection. That means kicking cancer booty!
But, we have to understand that these are screening tests, not diagnostic. That is a very important distinction. The makers of Cologuard state that if you have a family history of colorectal cancer, then you should consider more traditional screenings (such as colonoscopy or flex sigmoidoscopy). Just as a mammogram or ultrasound can reveal suspicious lumps (screening) it takes a biopsy (diagnostic) to diagnose.
These tests give us great hope for screening individuals that are at “normal” risk for the development of cancer. If you are at a high risk for the development of cancer, you should discuss your screening options with your doctor. Regardless of your choice of screening methods, these results should always be discussed with your physician for further evaluation.
Bottom line (in my humble opinion): know your risks, get screened, discuss with your doctor. Know your diagnosis before doing anything radical.
As always, much love, many prayers, and abundant blessings to all of the warriors out there!!