Early detection of cancer is the key to successful treatment, but since symptoms often do not appear in the early stages of cancer, regular testing is important. Blood tests have been attracting attention as a simple testing method for quickly detecting signs of cancer and can suggest the possibility of cancer through the measurement of specific tumor markers and general blood tests. Here we will explain the role of blood tests as cancer screening tests, their types, and their benefits.
1. Blood Tests to Detect Cancer
The following methods are mainly used to detect cancer using blood tests:
- Tumor marker test
- An increase in certain substances (tumor markers) in the blood may indicate the possibility of cancer. Tumor markers are substances produced by cancer cells or substances produced in the body due to the effects of cancer. The tumor markers measured vary depending on the type of cancer, and the following are some typical examples.
- AFP (alpha-fetoprotein) : Often elevated in liver cancer.
- PSA (Prostate-Specific Antigen) : Used to diagnose and monitor the progress of prostate cancer。
- CA125: Used to diagnose ovarian cancer
- CEA (carcinoembryonic antigen): May be elevated in colon cancer, stomach cancer, lung cancer, etc。
- CA19-9: A tumor marker used in pancreatic and biliary tract cancer。
- However, although tumor markers are indicators of the presence of cancer, they may rise even when there is no cancer, and conversely, there are cases where they do not rise even when there is cancer. Therefore, it is difficult to determine cancer with tumor markers alone, and diagnosis is generally made by combining them with other tests.
- General blood tests
General blood tests to check the components and cell status of your blood may also be helpful in identifying signs of cancer。- Abnormal white blood cell count: In leukemia, a cancer of the blood, the number and types of white blood cells may be abnormal。
- Presence or absence of anemia : If anemia is progressing, it may be due to colon cancer or stomach cancer. Chronic bleeding causes a decrease in red blood cell count and hemoglobin concentration.
- CRP (C-reactive protein) and inflammatory markers: Chronic inflammation may be related to cancer, and an increase in inflammatory markers may be seen.
- New blood testing technology (liquid biopsy)
Recent research has focused on technology that detects DNA and RNA released into the blood from cancer cells. This makes it possible to identify early cancer and metastasis and is expected to aid in cancer diagnosis in the future.
2. Benefits and limitations of blood tests
- Merit
- Easy to take: Blood tests are relatively easy to administer and are not invasive.
- Easier to detect early signs: Measuring tumor markers can help detect possible cancer at an early stage.
- Useful for follow-up monitoring: It can also be used to evaluate the effectiveness of cancer treatment and the risk of recurrence and can be useful in reviewing treatment plans.
- Limit
- Difficult to make a definitive diagnosis: An increase in tumor markers does not necessarily mean cancer, and they may increase due to inflammation or other diseases. Therefore, a definitive diagnosis of cancer cannot be made by blood tests alone.
- Effects vary by type of cancer: The usefulness of tumor markers varies depending on the type of cancer, and not all cancers have clearly elevated tumor markers.
3. Important points to remember when taking a blood test
- Regular checkups are important
To detect cancer early, it is important to undergo regular blood tests. People who are considered to be at high risk of cancer (such as those with a family history) should actively undergo tests. - Consult with a doctor
Even if abnormalities are found in the blood test, do not be overly anxious and be sure to consult with a doctor. It is important to make a comprehensive judgment based on other tests.
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