What Blood Test to Be Done for Cancer?

If you're wondering what blood test to be done for cancer, the short answer is that no single blood test can diagnose all cancers. Instead, healthcare providers use a combination of tests—such as a complete blood count (CBC), tumor marker panels, and emerging liquid biopsy technologies—depending on your risk factors, symptoms, and the specific cancer type suspected. Early detection through blood screening remains one of the most powerful tools in oncology, especially when paired with imaging and physical exams. Today, advancements in multi-cancer early detection (MCED) tests are making it possible to screen for dozens of cancers from a single blood draw, though traditional tests still play a vital role.

Why Blood Tests for Cancer?

Blood tests help identify biomarkers—substances produced by cancer cells or by the body in response to cancer. These markers can signal the presence of malignancy before symptoms appear, allow monitoring of treatment effectiveness, and indicate recurrence. In the US, cancer screening guidelines increasingly incorporate blood-based tests for certain high-risk populations. However, no blood test is 100% accurate; false positives and negatives occur, which is why confirmatory procedures like biopsies or imaging are often required.

Limitations and Role

Blood tests are not a standalone diagnostic tool. They are most effective when used as part of a comprehensive screening strategy. For example, elevated PSA levels may suggest prostate cancer but can also result from benign prostatic hyperplasia. Similarly, a high CA-125 level could indicate ovarian cancer but also occurs with endometriosis or pelvic inflammatory disease. Understanding these limitations helps you and your doctor interpret results correctly.

Common Blood Tests for Cancer Screening

Complete Blood Count (CBC)

A CBC measures red blood cells, white blood cells, hemoglobin, hematocrit, and platelets. While not specific for cancer, abnormal values can hint at leukemia, lymphoma, or other hematologic malignancies. Persistent unexplained anemia or extreme leukocytosis often prompts further investigation. The CBC is a routine, inexpensive first step in any cancer workup.

Tumor Marker Tests

Tumor markers are proteins or other substances elevated in certain cancers. Common examples include:

• PSA (prostate-specific antigen) – used for prostate cancer screening.
• CA-125 – associated with ovarian cancer.
• CEA (carcinoembryonic antigen) – monitored in colorectal and other cancers.
• AFP (alpha-fetoprotein) – linked to liver cancer and germ cell tumors.
• CA 19-9 – used in pancreatic cancer management.

These markers are often used for monitoring known cancers rather than initial screening, except for PSA which is widely used for early detection.

Circulating Tumor DNA (ctDNA) Tests

ctDNA tests, also called liquid biopsies, detect fragments of tumor DNA shed into the bloodstream. Today, these tests are becoming more mainstream for early detection of multiple cancers simultaneously. The Galleri test (from GRAIL) and similar MCED tests can screen for over 50 cancer types from a single blood draw, with a low false-positive rate. ctDNA is also used to monitor minimal residual disease after treatment.

When Should You Get Tested?

The decision to undergo blood testing for cancer depends on individual risk. Consider screening if you have:

• A strong family history of cancer (especially breast, ovarian, colorectal, or prostate)
• Unexplained weight loss, persistent fatigue, or lumps
• Age-appropriate screening recommendations (e.g., annual PSA for men over 50, or earlier for high-risk groups)
• Known genetic mutations (BRCA, Lynch syndrome, etc.)
• A history of smoking, heavy alcohol use, or occupational carcinogen exposure
• Abnormal findings on other screening tests that need further investigation

Comparison of Blood Tests for Cancer

Next Steps – Order Your Cancer Blood Test

Knowing what blood test to be done for cancer is the first step toward proactive health management. Whether you need a routine CBC, a tumor marker panel, or a multi-cancer early detection test, selecting the right lab and test quality matters. At anylabtests.com, we offer a wide range of US‑based, CLIA‑certified blood tests with physician-reviewed order processes. Take control of your health today. Order a comprehensive cancer screening blood test now and receive reliable results you can discuss with your doctor.