I’m going to take a holiday break from posting on this blog over the next few weeks. But before doing so, I’d like to share a few parting thoughts as we wrap up the year.
A few patients have recently asked me about “liquid biopsy” tests. These are a new frontier of testing in which a single blood sample is analysed for evidence of multiple types of cancer. The idea is to analyze a single blood sample and – ideally – receive reassurance. However if you got an abnormal result, you’d then be referred for further testing to either confirm or exclude a diagnosis of cancer. This is much the same process as our current prostate cancer screening program in which a man has a PSA test as part of his annual physical to indicate the possibility of prostate cancer and then, in the event of an abnormal result, is referred for further workup (e.g. a prostate MRI or biopsy) to determine if he in fact does have cancer, or if he simply has a “false positive.” However, unlike with a PSA – which checks only for prostate cancer – a “liquid biopsy” would be able to test for dozens of different types of cancer at once.
It’s wonderful to imagine a (not so distant) future in which a blood test at your annual physical can screen you for virtually every known type of cancer (including ones for which we currently have no good tools for early detection such as brain, pancreas, or ovarian) and either give you reassurance that you are cancer free, or conversely pick up a cancer in the very earliest stages and offer a much better chance for cure.
There are a number of such tests under development (the GALLERI test from Grail, and CANCERGUARD from the makers of Cologuard are two of the better known ones), and, as you can imagine, these are igniting great interest in both doctors and patients. And while none of these tests are yet to be FDA approved – nor to be covered by any type of insurance – a few are now commercially available for those who can pay out of pocket for them. Not surprisingly then, a few patients have asked me recently whether these are worth having.
I recently came across a paper that was published almost ten years ago (2017) but which I think is highly relevant and very interesting. But before I get into it, let me give a bit of context.
