Blood tests can directly detect blood cancers including leukaemia, lymphoma, and multiple myeloma through abnormal cell counts and protein levels. For solid tumours, blood tests measure specific tumour markers such as PSA for prostate cancer, CA-125 for ovarian cancer, CEA for colorectal cancer, and AFP for liver cancer. However, no single blood test can confirm cancer. Abnormal results always require further investigation through imaging or biopsy. Many common cancers including breast cancer, lung cancer, and brain tumours cannot be reliably detected through blood tests alone.
The reality, however, is more nuanced than many people expect. Blood tests can detect certain cancers particularly blood cancers like leukaemia and lymphoma but they cannot detect all cancers. For many solid tumours, including breast cancer and lung cancer, blood tests play a supporting role rather than providing a definitive diagnosis.
In this guide, we’ll explain exactly which cancers can and cannot be detected through blood tests, break down how tumour markers work with real reference ranges, and help you understand when booking a private blood test services might give you valuable peace of mind.
How Blood Tests Help Detect Cancer
Blood tests work by measuring substances in your blood that may indicate the presence of cancer. These include abnormal levels of blood cells, proteins, enzymes, and genetic material.
For blood cancers, the detection is often direct the cancer affects the blood cells themselves, so abnormalities show up clearly in routine tests like a Full Blood Count (FBC). For solid tumours, detection is indirect blood tests look for “tumour markers,” which are substances produced by cancer cells or by your body in response to cancer.
Cancer Research UK explains that blood tests are commonly used to check general health, assess organ function, and detect certain cancers, though they emphasise that most cancers require additional tests like imaging or biopsy for confirmation. This is why understanding what blood tests can and cannot do is essential before you book one.
Blood Cancers: What Shows Up Directly in Blood Tests
Blood cancers are the clearest example of cancers detected by blood tests because they originate in the blood, bone marrow, or lymphatic system. A routine Full Blood Count can often reveal the first signs.
Leukaemia
Leukaemia affects white blood cells and is frequently detected through a Full Blood Count showing abnormally high or low white cell counts, reduced red blood cells (anaemia), or low platelets. A peripheral blood film where a lab technician examines blood under a microscope can reveal immature “blast” cells that shouldn’t normally appear in circulating blood.
Lymphoma
Lymphoma affects the lymphatic system but can cause detectable blood changes, including elevated white blood cell counts and raised lactate dehydrogenase (LDH) levels. However, lymphoma typically requires a lymph node biopsy for definitive diagnosis, as blood tests alone aren’t conclusive.
Multiple Myeloma
Myeloma affects plasma cells in the bone marrow. Blood tests can detect abnormal immunoglobulin (antibody) levels, elevated calcium, kidney function changes, and abnormal proteins identified through serum protein electrophoresis. Blood Cancer UK notes that while blood tests are often the first step in identifying myeloma, a bone marrow biopsy is usually needed to confirm the diagnosis and determine the specific type.
Tumour Markers: How Blood Tests Detect Solid Cancers
For cancers that form in organs and tissues (solid tumours), blood tests rely on tumour markers substances that cancer cells release into the bloodstream or that your body produces in response to cancer.
Tumour markers are genuinely useful, but they come with important limitations. Elevated levels don’t always mean cancer, and normal levels don’t always mean you’re cancer-free. The NHS recommends that tumour marker results should always be interpreted alongside symptoms, imaging, and clinical assessment never in isolation.
Complete Tumour Marker Reference Guide
The table below shows the most common tumour markers, their normal reference ranges, the cancers they’re associated with, and crucially non-cancerous conditions that can also cause elevated levels. This information helps you understand why a single abnormal result doesn’t automatically mean cancer.
| Tumour Marker | Normal Range | Primary Cancer Association | Non-Cancerous Causes of Elevation |
|---|---|---|---|
| PSA (Prostate-Specific Antigen) | Below 4 ng/mL (varies by age) | Prostate cancer | Enlarged prostate, prostatitis, recent ejaculation, cycling, urinary infection |
| CA-125 | Below 35 U/mL | Ovarian cancer | Endometriosis, fibroids, pelvic inflammatory disease, menstruation, pregnancy, liver cirrhosis |
| CEA (Carcinoembryonic Antigen) | Below 3 ng/mL (non-smokers), Below 5 ng/mL (smokers) | Colorectal, lung, pancreatic, breast, stomach cancer | Smoking, inflammatory bowel disease, pancreatitis, liver disease, infection |
| AFP (Alpha-Fetoprotein) | Below 10 ng/mL (non-pregnant adults) | Liver cancer, testicular cancer | Hepatitis, cirrhosis, pregnancy |
| HCG (Human Chorionic Gonadotropin) | Below 5 mIU/mL (non-pregnant) | Testicular cancer, ovarian germ cell tumours, choriocarcinoma | Pregnancy, certain medications |
| CA 19-9 | Below 37 U/mL | Pancreatic cancer, bile duct cancer | Bile duct obstruction, pancreatitis, cholangitis |
| Chromogranin A (CgA) | Varies by lab | Neuroendocrine tumours | Proton pump inhibitor medications, kidney disease, chronic stress |
| LDH (Lactate Dehydrogenase) | 140-280 U/L (varies by lab) | Lymphoma, leukaemia, testicular cancer | Tissue damage, heart attack, liver disease, muscle injury, infection |
This table highlights a critical point: elevated tumour markers require context. A raised PSA in a 70-year-old man with urinary symptoms needs investigation, but it doesn’t automatically indicate cancer. Similarly, CA-125 can be elevated during menstruation in healthy women with no cancer whatsoever.
Cancers That Blood Tests Cannot Reliably Detect
Understanding what blood tests cannot do is just as important as knowing what they can do. Many common cancers do not produce reliable tumour markers or cause detectable blood changes in early stages.
Cancers Not Reliably Detected by Standard Blood Tests
| Cancer Type | Why Blood Tests Miss It | Recommended Screening Method |
|---|---|---|
| Breast cancer | No reliable blood tumour marker for early detection | Mammogram, clinical examination, biopsy |
| Lung cancer | CEA and NSE markers are not sensitive or specific enough for early detection | Low-dose CT scan (for high-risk individuals), chest X-ray, biopsy |
| Brain tumours | Most brain tumours don’t release detectable markers into blood | MRI scan, CT scan, biopsy |
| Skin cancers (melanoma) | No reliable blood marker for early detection | Visual skin examination, dermoscopy, biopsy |
| Kidney cancer | Often detected incidentally on imaging; no reliable blood marker | CT scan, ultrasound, MRI |
| Pancreatic cancer | CA 19-9 is often normal in early stages; elevated only in advanced disease | CT scan, MRI, endoscopic ultrasound |
| Bladder cancer | No standard blood test; detected through urine tests and cystoscopy | Urine cytology, cystoscopy, biopsy |
| Cervical cancer | Detected through cell changes, not blood markers | Cervical screening (smear test), HPV testing |
A normal blood test result does not mean you are cancer-free. If you have concerning symptoms unexplained weight loss, persistent fatigue, unusual lumps, changes in bowel habits, or bleeding you should see your GP regardless of your blood test results. The NHS advises that symptoms should always be investigated, even when initial tests appear normal.
What Happens If Your Blood Test Shows Abnormal Results?
Receiving abnormal blood test results can be alarming, but it’s important to understand that abnormal doesn’t automatically mean cancer. In fact, most abnormal tumour marker results have non-cancerous explanations.
Common Reasons for Abnormal Results (Without Cancer)
If your PSA is elevated, your doctor will consider factors like your age, prostate size, recent sexual activity, urinary infections, and whether you’ve recently cycled. An elevated PSA often leads to a repeat test in 6-8 weeks rather than immediate cancer investigation.
If your CA-125 is raised, your doctor will ask about your menstrual cycle, any history of endometriosis or fibroids, and whether you have any pelvic symptoms. According to NICE guidelines, CA-125 testing in primary care should be combined with an ultrasound scan and clinical assessment before any cancer referral.
If your blood count shows abnormalities, causes like iron deficiency, vitamin B12 deficiency, infection, or chronic disease are far more common than cancer. Your doctor will typically investigate these possibilities first.
What You Should Do
If your results are abnormal, your healthcare provider will discuss next steps, which might include repeat blood tests to confirm findings, imaging scans (ultrasound, CT, or MRI), referral to a specialist, or in some cases, a biopsy.
The key message is this: blood tests are a starting point, not a final answer. They help guide the diagnostic process, but they work best when combined with your symptoms, medical history, and other investigations.
New Advances: Multi-Cancer Early Detection Tests
The future of cancer blood testing is evolving rapidly. Multi-Cancer Early Detection (MCED) tests sometimes called “liquid biopsies” represent a significant advancement in cancer screening.
The Galleri Test
The Galleri test can detect over 50 types of cancer by analysing circulating tumour DNA (ctDNA) shed by cancer cells into the bloodstream. Research published by the National Institute for Health and Care Research (NIHR) shows that newer tests like TriOx are achieving detection rates above 90% for some early-stage cancers, with the ability to identify where in the body the cancer originated.
Availability in the UK
MCED tests are not yet part of routine NHS screening, but they are available through some private clinics. While promising, these tests are still being validated and refined. They complement but don’t replace established screening programmes like mammograms, cervical smears, and bowel cancer screening.
When Should You Consider a Private Blood Test?
A private blood test might be right for you if:
You have unexplained symptoms: fatigue, weight loss, night sweats, or persistent pain that your GP hasn’t fully explained
You have a family history of cancer: particularly if close relatives were diagnosed at a young age
You want proactive health monitoring: an annual health check to catch potential issues early
You’re monitoring a previous condition: tracking recovery or watching for recurrence
You want faster results: private testing often delivers results within days rather than weeks
Recommended Tests for General Cancer Awareness
| Test Type | What It Checks | Why It’s Useful |
|---|---|---|
| Full Blood Count (FBC) | Red cells, white cells, platelets | Detects blood cancers, anaemia, infection |
| Liver Function Tests (LFTs) | Liver enzymes, proteins | Identifies liver stress, potential liver cancer |
| Kidney Function (U&E) | Creatinine, urea, electrolytes | Checks kidney health, affected by some cancers |
| Inflammatory Markers (CRP, ESR) | Inflammation levels | Elevated in many cancers and infections |
| Iron Studies | Ferritin, iron, transferrin | Identifies anaemia, which can indicate hidden blood loss |
| LDH | Lactate dehydrogenase | Elevated in lymphoma, leukaemia, tissue damage |
A comprehensive health screen that includes these markers gives you a broad picture of your health. It won’t definitively diagnose cancer, but it can flag abnormalities that warrant further investigation.
Why Choose First Medical Consultants?
At First Medical Consultants, we make private blood testing simple, fast, and affordable. Our comprehensive health screens measure up to 150 biomarkers, giving you detailed insights into your health.
Our Health Screen Packages
| Package | Price | What’s Included | Best For |
|---|---|---|---|
| Basic Screen | £79 | Core health markers including FBC, liver, kidney function | Quick health MOT |
| Standard Screen | £119 | Expanded panel with thyroid and inflammatory markers | More detailed overview |
| Bronze Package | £139 | Comprehensive panel with diabetes and lipid markers | Cardiovascular and metabolic health |
| Silver Package | £199 | Extended panel with vitamins and hormones | Fatigue, energy, and wellbeing concerns |
| Gold Package ⭐ | £300 | Premium 150+ biomarker panel | Complete health picture |
| Tired All The Time | £149 | Targeted panel for fatigue investigation | Unexplained tiredness |
Why patients choose us:
- Results within 1-5 days
- Clear, jargon-free reports
- Clinics across the UK
- Competitive pricing with no hidden fees
- Support from qualified healthcare professionals
Ready to take control of your health? Call us on 0331 6300 850 or book online today.
Frequently Asked Questions
Blood tests can detect blood cancers including leukaemia, lymphoma, and multiple myeloma through abnormal cell counts and protein levels. They can also indicate some solid tumours through tumour markers PSA for prostate cancer, CA-125 for ovarian cancer, CEA for colorectal cancer, and AFP for liver cancer. However, blood tests alone cannot diagnose most cancers and are typically used alongside imaging and biopsy.
No. Many cancers including breast, lung, brain, and skin cancers do not cause detectable changes in routine blood tests, especially in early stages. A normal blood test result is reassuring but does not guarantee you are cancer-free. If you have symptoms, always follow up with your GP for further investigation.
Tumour markers are helpful but not definitive. Elevated levels can be caused by non-cancerous conditions for example, CA-125 can be raised by endometriosis, and PSA can be elevated by prostate infections. Conversely, some cancers don’t produce detectable tumour markers. Results must always be interpreted alongside symptoms and other tests.
There’s no universal recommendation, but if you have a family history of cancer, are over 50, or want proactive health monitoring, an annual comprehensive blood test is a sensible approach. This won’t screen for all cancers but can flag abnormalities worth investigating. NHS screening programmes (mammograms, bowel screening, cervical smears) remain important for specific cancers.
Private blood tests offer faster results, greater convenience, and access to comprehensive panels not always available through the NHS. They’re worth considering if you want proactive health monitoring, have specific concerns, or prefer not to wait for NHS appointments. However, they complement rather than replace NHS care and screening programmes.
A tumour marker test measures substances in your blood that may be produced by cancer cells or by your body in response to cancer. Common tumour markers include PSA, CA-125, CEA, and AFP. These tests are most useful for monitoring known cancers or detecting recurrence, rather than screening for new cancers in people without symptoms.
There is no single biggest indicator. However the most clinically significant markers are an abnormal Full Blood Count showing unexplained anaemia, elevated white blood cells, or low platelets combined with elevated inflammatory markers such as CRP and ESR. For specific cancers, a raised PSA in men or elevated CA-125 in women represent the most commonly acted-upon individual markers. No single result confirms cancer markers are always interpreted alongside symptoms and imaging.
Depending on the cancer type, blood tests may show abnormal white blood cell counts, reduced red blood cells or haemoglobin indicating anaemia, elevated tumour markers such as PSA, CA-125, CEA or AFP, raised inflammatory markers including CRP and LDH, abnormal protein levels particularly in myeloma, and in advanced testing, circulating tumour DNA fragments. Different cancers produce different changes no single abnormality is universal across all cancer types.
Blood test warning signs that may prompt further cancer investigation include unexplained anaemia with low haemoglobin, persistently elevated white blood cell count without infection, low platelet count with no obvious cause, raised LDH levels, elevated inflammatory markers such as CRP and ESR that do not resolve, abnormal protein levels detected on electrophoresis, and elevated tumour markers including PSA, CA-125, AFP, or CEA above normal reference ranges. These findings do not confirm cancer but indicate that further investigation is needed.
Conclusion
So, what cancers are detected by blood tests? The answer is nuanced but important to understand.
Blood tests can directly detect blood cancers like leukaemia, lymphoma, and myeloma through abnormal cell counts and protein levels. They can also indicate the possible presence of some solid tumours through tumour markers such as PSA, CA-125, CEA, and AFP though elevated markers require further investigation and don’t confirm cancer on their own.
Blood tests cannot reliably detect many common cancers, including breast cancer, lung cancer, brain tumours, and skin cancers. For these, imaging and biopsy remain essential diagnostic tools.
Understanding these limitations is just as important as knowing the capabilities. A blood test is one valuable piece of the diagnostic puzzle not the whole picture.
If you’re concerned about cancer or simply want peace of mind, a comprehensive private blood test can provide useful insights into your health. Combined with regular NHS screening programmes and attention to any new symptoms, proactive testing helps you stay ahead of potential problems.
Ready to take the next step? Book your private blood test with First Medical Consultants today, or call us on 0331 6300 850 to speak with our team.
