Possible screening tests for cancer

As a naturopathic doctor, many of my patients in health conscious Richmond and Vancouver frequently are pro-active in preventing and treating disease early. Of course, this involves the basics of physical activity, proper diet, and mental/emotional health. When I have a patient who is lucky enough to not have a serious chronic disease and is most interested in overall prevention, I run conventional but comprehensive blood work that evaluates how the body is functioning. Along with a screening physical, often times we can catch elevated risk for common but potentially serious chronic disease such as heart disease and diabetes.

Typically, for those patients who may have less than stellar physical activity or diet, the blood work would also include risk factors for coronary artery disease and diabetes. This would include the very common cholesterol and lipid panels, as well as a fasting blood sugar. From a naturopathic approach, I would take it further for my Vancouver and Richmond patients and measure the hormone that controls blood sugar (insulin, as elevated levels can catch diabetes earlier than a fasting sugar), as well as run an inflammation test (highly sensitive CRP) and lipid fractionation. The inflammation test is an independent risk factor for heart attacks and stroke, and lipid fractionation tells us how likely a patient's LDL or bad cholesterol is likely to cause plaque. We might even go so far as to get a heart scan in order to the amount of calcified plaque in the arteries.

However, when it comes to cancer, things are much more difficult when trying to detect a marker in the blood. The most important thing is still conventional, age or symptom appropriate screening. An example of such is colonoscopy for patients older than 50, or earlier particularly if there is a family history. Fecal occult blood is another screen that is appropriate for many patients and inexpensive.

Is there a blood test that can tell me about cancer?

This is a common question that patients ask me. The answer is really no, that there is no widely accepted blood test that tells us if a patient has cancer. Particular types of cancers can release tumor markers in the circulation that lead one to suspect cancer, but these are typically used for monitoring treatment and recurrence, not for screening. For example, many gastrointestinal cancers secrete CEA in the blood, which if elevated in a known cancer patient provide one way to monitor treatment.

CEA itself is called a "tumor marker" but is not used for widespread screening because not all gastrointestinal cancers produce this marker. Thus, if a patient is does not have any symptoms or any known cancer, if the CEA level is normal, it does not definitively say there is no gastrointestinal cancer. Conversely though, if the CEA level is elevated, it is highly suspicious for cancer, and a search needs to be undertaken.

Because of that last point, and the fact that there are a smattering of different cancer markers for different cancers, some very proactive patients like to be on the safer side and take every chance they can for early detection. Thus a battery of tumor markers are typically run by myself which include:

• CEA (many cancers, but colon and other gastrointestinal especially)
• CA19-9
• CA125
• CA15-3
• AFP

The limitation of the above tests is again that a patient could have cancer but have a negative test if that cancer is not producing the markers. But if they are elevated, then there may be early detection. Another limitation is that the markers are often specific for only one organ system.

A newer tumor marker which screens for a larger variety of cancers

DR-70 is a newer tumor marker that seems to be more sensitive than many of the above. It is known by its more scientific name tumor associated fibrin and fibrin degradation products, or tFFDP.

• cancer cells secrete proteins called proteases (plasmin and thrombin)
• these cancer related proteases digest components in the blood such as fibrin
• tumor fibrin and fibrinogen degradation products levels rise with cancer progression as plasmin breaks down the fibrin
• tFFDP levels (DR70 test) rise dramatically with cancer progression, up to almost 40 times normal

What research is published?

8 clinical trials have been performed.

The cost of the test is $210 USD, and needs overnight shipping (usually around $60), not including the office visit.

If the test is positive, it does not definitively say that a patient has cancer (thus having the similar limitation as other tumor markers), but the suspicion is very high and thus a search begins for the source of the cancer. Only a few things can cause it to be elevated in non-cancer cases, including smoking, recent surgery, or recent severe infection. And these will not raise it as high as typically seen in cancer. More importantly, a negative result does not say that there is no cancer definitively. Thus, it absolutely does not replace conventional appropriate tests and screening (such as a colonoscopy). However, it does serve the purpose for patients looking for tests that give early detection, and can serve as a marker to monitor naturopathic therapy.

 

Again, being a naturopathic doctor in health conscious Richmond and Vancouver, some of my patients are very health conscious. Many are originally from other countries where doctors do check tumor markers in the blood, understanding the limitations discussed above but encouraged by the possibility of early detection - often these patients already come to me having had these tests run.  For those health conscious Vancouver and Richmond patients seeing a naturopath for optimal health and disease prevention, a panel of the above markers may be useful.