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Explore the details on “Can cancer be determined by a blood test?” and the specialized procedures that are used to diagnose cancer. Learn more!

Blood tests are useful in diagnosing many critical diseases; however, one significant query that often comes to the mind of many people is “Can cancer be determined by a blood test?” A  2025 study published in Cancer Discovery reported that plasma cell-free DNA (ctDNA) could detect multiple cancers up to three years before a clinical diagnosis. However, these tests can not replace specialized cancer detection tests like biopsies or imaging that are specifically used to confirm cancer.

Plus, doctors use advanced methods to confirm cancer diseases like lymphoma, leukaemia, multiple myeloma, and others. 

So, blood tests alone are not enough to diagnose cancer, they work with other procedures.

To make you aware, we will guide you about the capabilities of blood tests in cancer detection and what types of tests can be effective in finding cancer diseases. But, before delving into the details, quickly jumpstart with table below for a brief overview of the blood tests:

Blood Test type

1. What It Mesure
2. What It Can Identi

Key Notes

Complete Blood Count (CBC)	RBCs, WBCs, platelets	Leukemia, lymphoma, bone-marrow problems	Often, first test if cancer is suspected
Tumor Markers	Proteins/chemicals made by cancer cells (e.g., PSA, CA-125, CEA)	Possible presence of specific cancers	Not enough alone for diagnosis
Blood Protein Tests	Abnormal immune system proteins	Multiple myeloma or related disorders	Uses protein electrophoresis
Circulating Tumor Cells (CTCs)	Whole cancer cells in the bloodstream	Cancer spread, treatment monitoring	More common in research settings
Circulating Tumor DNA (ctDNA) / Liquid Biopsy	DNA fragments shed by tumors	Gene mutations, treatment response, and recurrence	Growing role in precision medicine

What are the main types of Blood Tests that Doctors use to Diagnose Cancer?

For cancer detection, doctors and health professionals use five distinct types of blood tests, including complete blood count (CBC), blood protein tests, tumor marker tests, circulating tumor cell (CTC), and circulating tumor DNA (ctDNA) / Liquid biopsy tests. 

These tests measure several cells and substances in the blood. All types of tests are functional to detect certain kinds of cancers. Let’s look into the details of how these tests work:

Complete Blood Count (CBC) 

The CBC fundamental test is used to analyze the different components of blood. A haematocrit and haemoglobin level are checked along with the number of white blood cells, red blood cells, platelets, and haematocrit. 

However, the test specifically works to monitor blood cancers such as lymphoma and leukaemia. It works to identify major organ cancers like breast, lung, or colon cancer.

Tumour Marker Blood Tests

This test specifically diagnoses how chemicals are moving in the bloodstream. The average tumor marker blood test is CA-125, which helps in planning treatment as well as detecting the recurrence of pancreatic and ovarian cancers. 

PSA Test

The PSA test measures the quantity of prostate-specific antigen in the blood, a protein made by the prostate gland. 

Higher PSA levels in the blood can suggest prostate cancer, although they can also be caused by BPH or prostatitis. 

Thus, an elevated PSA result leads a doctor to do more testing to determine the cause.  

Blood Protein Tests 

Doctors often perform this test to measure abnormal protein levels. It detects the specific types of cancer. 

Primarily, it is used to monitor blood cancers like lymphoma, leukaemia, and multiple myeloma. Blood protein tests are often part of a full metabolic panel that tells about protein amounts.  

Circulating Tumour Cell (CTC) Tests

CTC tests are more advanced in diagnosing small pieces of tumors that split and circulate through the bloodstream. Doctors use CTC tests to guess what will happen to people whose breast, prostate, or bowel cancer has spread. 

In fact, a low number of CTCs does point to a good result, while a high number of CTCs could mean that more treatment is needed. 

Does Early Cancer Diagnosis through Blood Work?

Most cancers aren't diagnosed in routine blood work. They require specialized blood tests to identify early-stage cancers in some people. Beyond the main groups, here is the detail of specialized blood tests:

The Galleri test

The Galleri test is a complex screening tool. With just a blood draw, it can indicate signs of several types of cancer. 

This test is more helpful for people aged 50 because they face 13 times more cancer risk than younger people.

Proteomics-based Plasma Test

A plasma test based on proteomics has shown a lot of value in finding cancer early. According to research, this test was able to find 93% of Stage I cancers in men and 84% of Stage I cancers in women, including 18 different types of cancer 3.

Therefore, tests that look for circulating tumor DNA (ctDNA) can find small pieces of tumor DNA in the blood. According to research, the rates of finding ctDNA are related to the stage of the cancer. For stage one, the rates are 47%, for stage two, they are 55%, for stage three, they are 69%, and for stage four, they are 82%. 

Why do Cancer Detection Need more Diagnostic Modalities than Blood Tests?

Along with blood tests, doctors use other testing tools to definite cancer. Even though blood tests have come a long way, without advanced evidence, one test alone can't be sure that someone has cancer.

Here are the details of the blood tests required for accurate cancer detection:

1. Biopsies: To detect cancer, these procedures are essential. They monitor tissues. The process involves taking tissue samples from organs and bone marrow and then analyzing them in the lab. Here are some popular types of biopsies: 
2. Bone marrow biopsies
3. Endoscopic biopsies
4. Skin biopsies
5. Needle biopsies
6. Special screening tests: These tests are used to detect specific cancer types like Pap checks are performed for cervical cancer, while colonoscopies work for colorectal cancer detection, and scans work better to monitor breast cancer. 
7. Imaging tests: MRI, PET, CT, and bone scans, X-ray, and ultrasounds are also used to diagnose cancer diseases.
8. Bronchoscopies help in finding lung cancer, and myelograms help in identifying tumors in the spinal cord.

How does Lab Analysis Aid in Accurate Diagnosis?

An accurate cancer diagnosis requires laboratory analysis. It provides objective, quantifiable evidence to validate or deny a condition. Also, it identifies underlying pathologies and tracks disease progression. 

Although doctors do clinical assessments based on symptoms and physical exams to ensure solid clues. However, lab results give a definitive, evidence-based determination of a patient's health. 

Beyond the simple blood examination, laboratory analysis is used because chemical procedures measure the levels of different components of bodily tissues and fluids. Here is the list of the lab parameters:

1. Electrolyte levels
2. Blood glucose
3. Enzyme activity
4. Hormone levels
5. Protein concentrations

However, around 60% of cancer deaths are caused by malignancies without screening tests. Blood testing may replace costly imaging treatments, minimize radiation from image-based screening, and remove certain invasive procedures. 

Key Note

It is recommended to consult with doctors for better advice regarding cancer tests. The implications of blood test findings for future testing must be reviewed with experienced specialists.

How Can You Support Cancer Patients Getting Blood Tests?

As we explore “Can Cancer be Determined by a Blood Test?”It makes one thing clear that if people access blood tests, early detection of cancer is possible. Organizations like Noor Thalassemia Foundation provide blood related treatments to the needy people. 

However, they depend on donations to provide essential diagnostic services to children and families affected by blood disorders. This is where community support becomes important. 

Therefore, if you can support a life-saving blood test, why wait? Extend your hand to donate to people struggling with blood diseases. Your aid helps provide blood tests, screenings, and early-detection programs, ensuring vulnerable patients receive timely care and a stronger chance at healthier outcomes.

Conclusion

Hence, after this in-depth analysis, you might be able to understand now, “Can Cancer be Determined by a Blood Test?” While talking about cancer diagnosis, blood tests seem effective. But, a routine blood test can't detect cancer but works best alongside other diagnostic methods. 

However, in this advanced era, doctors adopt several effective blood test procedures to confirm cancer. From Complete blood count (CBC) tests, tumor markers to Circulating tumour cell tests, and more, every method is used in cancer indication. These tests require just small blood samples and provide accurate results. 

Moreover, some non-profit organizations also offer blood-related treatment to needy people who can't afford expensive blood tests and procedures. But they depend on the continuous community support and donations to save the lives of thousands of people. By donating funds, Zakat, and charities, you can participate in this kind act and bring a smile to someone’s face.

FAQs

Which test helps to identify cancer?

Not a single test can diagnose all cancers; multiple methods are used to confirm cancer detection. Imaging tests such as MRI, CT, and PET scans are used to identify tumors, while a definitive biopsy is required for tissue examination. 

However, for abnormal cells or marker detection, blood or urine tests are performed. So, the use of specific tests depends on the location and suspected type of cancer.  

What Blood test markers are high in Cancer?

Tumor Marker	Cancers Associated With Elevated Results
LDH Lactic Dehydrogenase	Lymphoma, melanoma, acute leukemia, seminoma (germ cell tumors)
NSE Neuron-specific Enolase	Small cell lung cancer**, neuroblastoma
NMP 22 (urine test)	Bladder cancer**

What are the main Blood Tests that are used to Diagnose Cancer?

To identify cancer, complete blood count (CBC), circulating tumour DNA (ctDNA), tumour markers, and liquid biopsy are commonly used.

How Accurate are Blood Tests in Detecting Cancer?

Some blood tests give valuable indicators, but usually they can’t be definitive. Healthcare professionals often use advanced tests, like scans and biopsies to accurately diagnose cancer.