Obviously, a false diagnosis of cancer would be a disaster.
I’m not talking about all tests for cancer. I’ve only looked into two. This is what I’ve discovered.
There is a blood test, which looks for a bio-marker labeled CA125. There are doctors who will tell you that a highly positive result indicates a high probability of cancer.
Imagine being a patient on the receiving end of that news.
But wait. If you go to other sources—and no, I’m not talking about alternative practitioners, I’m talking about the mainstream—you’ll get a distinctly different view.
How about a quite prestigious organization—the Mayo Clinic?
“A CA 125 test measures the amount of the protein CA 125 (cancer antigen 125) in your blood.”
“A CA 125 test may be used to monitor certain cancers during and after treatment. In some cases, a CA 125 test may be used to look for early signs of ovarian cancer in people with a very high risk of the disease.”
“A CA 125 test isn’t accurate enough to use for ovarian cancer screening in general because many noncancerous conditions can increase the CA 125 level.”
“Many different conditions can cause an increase in CA 125, including normal conditions, such as menstruation, and noncancerous conditions, such as uterine fibroids. Certain cancers may also cause an increased level of CA 125, including ovarian, endometrial, peritoneal and fallopian tube cancers.”
“Your doctor may recommend a CA 125 test for several reasons: But such monitoring hasn’t been shown to improve the outcome for those with ovarian cancer, and it might lead to additional and unnecessary rounds of chemotherapy or other treatments.”
“…some people with ovarian cancer may not have an increased CA 125 level. And no evidence shows that screening with CA 125 decreases the chance of dying of ovarian cancer. An elevated level of CA 125 could prompt your doctor to put you through unnecessary and possibly harmful tests.”
“A number of normal and noncancerous conditions can cause an elevated CA 125 level, including:
• Liver disease
• Pelvic inflammatory disease
• Uterine fibroids”
“None of the major professional organizations recommend using the CA125 as a screening test for those with an average risk of ovarian cancer.”
Is that clear enough? I hope so.
Let’s move on to another test for cancer. It’s a version of a PET scan.
From acrin.org, About PET Scans: “A PET scan uses a small amount of a radioactive drug, or tracer, to show differences between healthy tissue and diseased tissue. The most commonly used tracer is called FDG (fluorodeoxyglucose), so the test is sometimes called an FDG-PET scan. Before the PET scan, a small amount of FDG is injected into the patient…”
The theory goes this way: cancer cells have an affinity for FDG and “grab on to” it. Thus, these cancer cells “light up” on the PET scan and can easily be seen. Tumors and metastases can be observed.
Introduction to PET/CT Imaging: “Cancer cells are not always the only ‘PET avid cells’ (or cells that take up the FDG) in the body. It is important to remember that a PET scan is not able to distinguish metabolic activity due to tumor from activity due to non cancerous processes, such as inflammation or infection.”
PET scan findings can be false positive: “In cancer cells, there is an overproduction of glucose transporters and, as a result, increased FDG uptake. However, not all PET-positive lesions are cancer, and in many instances, PET findings can be false positive. … Inflammatory cells also have increased metabolic rates and, as a result, are FDG avid.”
“Many of us have had patients or know of patients who were treated by the medical oncologist for stage IV cancer only to find out what was assumed to be a metastatic lesion was benign on pathology. Other patients have undergone multiple biopsies of supposed metastatic mesenteric lymph nodes that subsequently turned out to be fat necrosis or a granulomatous reaction. FDG-positive lesions often mean cancer, but not always. A variety of lesions have increased FDG radiotracer [the "lighting up” phenomenon] including infection, inflammation, autoimmune processes, sarcoidosis, and benign tumors. If such conditions are not identified accurately and in a timely manner, misdiagnosis can lead to inadequate therapies.”
Causes and imaging features of false positives and false negatives on 18F-PET/CT in oncologic imaging: Causes and imaging features of false positives and false negatives on 18F-PET/CT in oncologic imaging“Glucose however acts as a basic energy substrate for many tissues, and so 18F-FDG activity can be seen both physiologically and in benign conditions. In addition, not all tumors take up FDG [3[3–5]The challenge for the interpreting physician is to recognize these entities and avoid the many pitfalls associated with 18F-FDG PET-CT imaging.”
The question is, after a patient is told he has received a positive PET scan, indicating cancer, will the physician spell out all the factors that could have made the test read FALSELY POSITIVE? Will an intelligent and honest and informed conversation take place, or will the doctor shove the test results at the patient and declare: “You have cancer.”
And if that cancer diagnosis is given, will the patient be in a position to voice questions through prior knowledge, and undertake a reasonable dialogue with his doctor?
How do doctors normally hand down test findings? In a balanced way, or from on high, with all the presumed authority of unchallengeable experts?
Are there doctors who don’t even know these two diagnostic tests are rife with falsely positive readings? Yes, there are. And if they deliver papal edicts based on their ignorance, they can cause great harm.