About 40% of Americans will experience cancer over our lifetime. Some of these cancers have screening tests but even those are imperfect. They may miss the cancer (false negative), or have a false positive. They may find a tiny tumor that is “indolent” and would never have become deadly if left alone. They may find a tumor after it has already metastasized. Some cancers metastasize very early and even small tumors are too late to treat effectively.
Most of the current screening tests are expensive and can be uncomfortable. (e.g. mammograms) Many dangerous cancers (e.g. ovarian, pancreatic) have no test at all so they are often too far gone to cure by the time they produce symptoms.
Wouldn’t it be nice to have a simple blood test that would detect all cancers, accurately and at a treatable stage? Some call this a “liquid biopsy.”
**Blood Tests That Detect Cancers Create Risks for Those Who Use Them**
**The tests screen for cancers that often go undetected, but they are expensive and some experts worry they could lead to unnecessary treatments without saving patients’ lives.**
**By Gina Kolata, The New York Times, June 10, 2022**
**The tests, which look for minuscule shards of cancer DNA or proteins, are a new frontier in screening. Companies developing them say they can find dozens of cancers. While standard screening tests are commonly used to detect cancer of the breast, colon, cervix and prostate, but 73 percent of people who die of cancer had cancers that are not detected by standard tests....**
**“GRAIL proposes to test every Medicare beneficiary every year, making it the screening test that could bankrupt Medicare...” ....With 44 million Medicare beneficiaries and an annual test costing about $1,000 a year plus expensive scans and biopsies for those whose tests are positive, the price tag could be substantial....**
All the problems with current screening tests apply, and then some.
There hasn’t been a statistical study to show whether patients who have the “liquid biopsy” have better survival rates than those who use conventional screening. The tests have not been approved by the FDA but are selling to the public anyway. People who get a positive result then go the conventional route of trying to find where the tumor is located and how to treat it.
There is already controversy about conventional screening tests like mammograms and low-dose spiral CT scans to detect lung cancer. They are costly and only find a few cancers per thousand tests – but those detections may be life-saving. The bean-counters are trying to raise the age of routine mammograms to 40 in the U.S. (50 in the U.K.) but that would miss thousands of younger women with cancer (though a small fraction of the total population).
Routine liquid biopsies would lead to such high expenses that they would have Macro impact on Medicare. And the patients with the positive results may be sent on a painful and expensive course of treatment that might be unnecessary.
Would you get a liquid biopsy as routine screening?
I would because I have already had breast cancer, first diagnosed in 2013 as tiny (0.5 cm) bilateral tumors by MRI. This was Stage 1 and my treatment was apparently successful. (Bilateral mastectomy and 5 years of aromatase inhibitor.) But there is a slight risk that a dormant cancer cell could be hiding in my bones which could awaken later. This happened to a woman in my breast cancer support group after 17 years; she died less than a year later.