Blood tests are routine procedures that most people encounter when seeking a medical diagnosis, but can a blood test detect cancer in the body?
Traditionally, cancer screenings have required physical examines and a differential diagnosis based on symptoms to narrow in on cancer as the cause of healthcare conditions.
These days, however, blood tests like the multi-cancer early detection (MCED) test can be used to provide precise measurements of cancer cells in the body.
What Are MCED Tests?
An MCED is a test that can show cancer markers in blood taken during routine office visits with a physician. Currently, the most common MCED test is Galleri which can detect up to 50 different types of cancer. When cancer cells undergo mitosis, or the process of cell division and replication, biomarkers are shed and left behind, often circulating in bodily fluids like blood.
It’s these biomarkers that can be signs of cancer in blood work that tests like Galleri use to identify not only the type of cancer but also its place of origin in the body.
Other Types of Blood Screenings For Cancer
A complete blood count (CBC) is another common type of blood test to detect cancer. A CBC measures, among other things, the levels of important coagulation factors that may show a need to investigate further.
The liver plays a large role in clotting factor formation, so a CBC that shows low platelets along with an above-average prothrombin time (PT), as well as an above average international normalized ratio (INR), may indicate cancers like leukemia.
Serum alkaline phosphatase (ALP) is another type of blood test to detect cancer in the colon, pancreas and liver. This test looks for a specific ALP biomarker that can indicate liver cancer, gallbladder cancer or biliary cancer. Additionally, an ALP blood test that returns elevated levels of alkaline phosphatase may be indicative of other types of cancers, including lung cancer and testicular cancer.
Experimental And Emerging Blood Tests For Cancer
Although the above examples of blood tests for cancer detection provide physicians and specialists with a high degree of accuracy in diagnosing cancer, they are not without their drawbacks.
Because most blood tests can only point a doctor in the right direction instead of providing clear evidence of cancer, more tests are usually required to be used in conjunction with other exams. Typically, imaging techniques like magnetic resonance imaging (MRI) and x-rays are used in addition to blood tests to confirm a diagnosis.
Additionally, blood test indicators of cancer only show up when cancer has already appeared in the body, meaning it’s usually too late to take preventative measures.
Scientists are currently investigating experimental blood tests that have the potential to detect cancer before it becomes active in the body. The PanSeer test is an example of such a test, and it was developed by examining blood samples of cancer-free subjects for years.
PanSeer examines methylation patterns and DNA to detect changes in genetic activity. Abnormal methylation behavior has been correlated with the presence of cancers of the pancreas and colon. Currently, the PanSeer test has been shown to provide accuracy rates as high as 90% and false positives at a rate of 5%.
The genetic technology behind the PanSeer test and other blood tests for cancer detection could signal a new approach to preventative medicine by recognizing individuals who are predisposed to developing cancer before the disease begins to grow and cause symptoms.
Researchers are also investigating emerging blood tests to work in tandem with low-dose computer tomography (LDCT) tests. LDCT technology can identify cancers using low doses of radiation and computerized tomography mapping, but these tests can lead to false positives.
This may result in unnecessary biopsies or other invasive procedures. New blood tests are being developed to support LDCT result verification by examining specific biomarkers in the blood that may reduce the number of false positives and help doctors to differentiate between non-small-cell lung cancers and benign tumors and growths.