Can a blood test detect cancer?

A friend mentions a blood test that checks for cancer. Or someone close to you has just been diagnosed, and you want to know, quickly and simply, whether you're clear. One tube of blood, one number, one answer: it's an appealing idea.

The short answer is that a blood test can't detect cancer in the way most people hope. It can show metabolic risk, and some packages add tumour markers, which are clues. Those clues need a doctor, an examination and often imaging before they mean anything. A raised marker isn't a diagnosis, and a normal one isn't an all-clear.

If you'd rather skip the reading, the Elite Health MOT puts tumour markers beside an examination and ultrasound at our Harley Street clinic. It costs £1,850 for men and £2,095 for women. If your question is about one organ, start with our cancer screening packages, which use the test that organ needs.

What does a routine blood test actually show?

Screening has a precise meaning. The UK National Screening Committee describes it as identifying apparently healthy people who may have an increased chance of a disease or condition. Screening tests tend to be simple rather than very accurate, and they often need further tests to confirm or exclude disease. Paying privately doesn't change that.

At The Health Screening Clinic, the Essential MOT is a doctor-led baseline at 117a Harley Street. Its bloods are metabolic: full blood count, kidney and liver function, lipids, glucose and HbA1c, thyroid, iron, inflammation and bone chemistry. That panel can flag anaemia, diabetes risk, cholesterol, thyroid change and strain on the liver or kidneys. Those are useful findings in their own right, and they answer a different question from cancer.

A full blood count can sit outside range because of an infection, low iron or a medicine, with no tumour involved. Raised cholesterol starts a conversation about your heart, and HbA1c tells you about glucose control. Essential gives you a GP consultation, a physical examination and a reviewed metabolic panel, without CEA, PSA or CA-125. Book it when a metabolic baseline is what you're after.

Why are tumour markers clues and not answers?

Tumour markers are proteins that some cancers produce. The catch is that ordinary tissue can produce them too. CEA, PSA and CA-125 can be raised when there's no cancer, and they can sit inside the laboratory range when cancer is present. That double weakness is why the UK National Screening Committee has not recommended a national programme built on a general cancer blood test.

NICE suspected-cancer guidance (NG12) uses PSA and CA125 for people who already have symptoms. For persistent symptoms that suggest ovarian cancer, NICE recommends measuring CA125 in primary care, then arranging an ultrasound depending on the result. The UK NSC does not recommend population screening for ovarian cancer. The UKCTOCS trial found that screening with CA125 or ultrasound did not reduce deaths from the disease.

PSA works the same way. NHS pages are clear that a high PSA may come from an enlarged prostate or another non-cancer change. Inflammation, infection, recent ejaculation, cycling and breathless exercise can all lift it, and a low result is no lifetime guarantee either. Routine PSA testing isn't offered on the NHS as a population programme, though men can discuss the test with a GP. The UK NSC still does not recommend population prostate screening.

CEA is mainly used to watch for recurrence in people already known to have bowel cancer. Smoking, inflammatory bowel disease, liver disease and other adenocarcinomas can lift it, and early bowel cancer often leaves it normal. That's why the NHS bowel programme uses a stool FIT kit instead of a CEA blood test.

Some clinics offer a wider cancer blood test, often called a liquid biopsy. We offer one, Trucheck, which looks for circulating tumour cells, as part of Whole Body Cancer Screening at £3,499. It sits outside any NHS programme and has not been shown to reduce cancer deaths. It works alongside the NHS breast, cervical and bowel programmes and alongside imaging of a named organ, and every result still needs clinical review.

Where markers earn their place: Elite and Ultimate

Elite is the MOT that adds tumour markers, because it already includes the examination and imaging those markers would need if one flags. It includes CEA for everyone, PSA for men over 40, and CA-125 for women, alongside gender-specific ultrasound. Women also have a mammogram from 40, a smear and consultant gynaecology. The marker is read with the pictures and the person on the couch, never as a lone number on a PDF.

The Ultimate Health MOT adds HE4 and a ROMA score for women, on top of CA-125. ROMA is a calculation that combines HE4, CA-125 and menopausal status. When a doctor is already looking at pelvic imaging and your history, those extra markers can refine the risk picture. They remain information for the doctor, not a verdict.

Choose Elite when you want markers inside a doctor-led assessment that already includes ultrasound and specialist input. Essential is the better fit when a metabolic baseline is the question you have.

Why every MOT puts bloods next to an examination

Laboratories mark results against a reference range, which is a statistical interval and not a medical sentence. A flag means look again with the rest of the picture. On its own, it can't tell you whether you have cancer.

That's why every MOT at the clinic includes a GP consultation, a physical examination and an in-person review of the report. Blood numbers alone leave you with a clue and no map. Imaging alone gives you a picture with no chemistry. Read together, with a doctor who has examined your abdomen, considered your prostate or assessed your breasts, they answer different parts of the same question.

If a marker is raised, the doctor who examined you decides whether to repeat it, watch it, add a scan or refer you. If it's ordinary, the same doctor still has the examination and the imaging to go on.

Our packages are built for people who feel well enough to be screened. If you have new, severe or worsening symptoms, see a GP or get urgent assessment, and in an emergency call 999 or go to A&E.

When your question is about one organ

A MOT from our Health MOT menu is a wide preventative assessment. When your question is about one organ, a named cancer-screening package puts the right test in the room:

• Prostate: PSA read with an examination and, on the tiers that include it, prostate MRI.
• Breast: a mammogram from 40, with ultrasound or MRI according to age and breast density. No breast tumour marker can stand in for those pictures.
• Bowel: quantitative FIT and, when imaging is the question, CT colonography.
• Lung, if you have smoked: low-dose CT, which can see a small nodule that a metabolic blood panel can't.

Keep going to the NHS breast, cervical and bowel screening you're invited to. Those programmes exist because the tests, in those age groups, have evidence behind them, and the UK NSC recommends them. Private screening, whether a MOT or an organ package, works best alongside them.

Getting the most from your appointment

• If cancer runs in your family, tell us, and bring previous bloods, smears, mammograms, PSA figures and clinic letters. The doctor is reading a trend and a person, not a single printout.
• Fast only if the clinic has asked you to for the tests you've booked, and keep taking your regular medicines unless you're told otherwise.
• Before a PSA test, follow the 48-hour advice on the NHS page: no ejaculation, anal sex, breathless exercise or cycling. After a urine infection, wait four to six weeks once it has cleared.
• Leave time for the review appointment. That's where a flag becomes a plan.

The organ packages and the wider MOT are on our cancer screening page. Or call The Health Screening Clinic on 020 7183 7056. For what each marker on the MOT menu does, read tumour markers in a MOT. For one organ versus the whole body, whole-body cancer screening versus an organ package sets out the difference.

Frequently asked questions

Can a blood test detect cancer?

Not on its own. A blood test can show metabolic risk and, in some packages, tumour-marker clues, which need an examination and often imaging before they mean anything. A raised marker isn't a diagnosis, and a normal one isn't an all-clear.

Are the Essential MOT bloods a cancer screen?

They're a metabolic baseline: blood count, kidney and liver function, lipids, glucose, thyroid, iron and related chemistry. Tumour markers start at Elite.

What do CEA, PSA and CA-125 show?

They're tumour-marker clues included in the Elite MOT. NICE NG12 uses PSA and CA125 for people with symptoms, not as general cancer tests, and each can be raised for non-cancer reasons or normal when cancer is present.

Does a normal marker mean I don't have cancer?

It means that marker was in range on the day. Markers can miss disease as well as over-flag it, so the doctor reads them with the examination and any imaging in your package.

When should I book an organ package instead of a MOT?

When your question is about a named organ: prostate, breast, bowel or lung. An organ package uses the test built for that organ, while a MOT is a wide preventative assessment.

What if I have a new or worsening symptom?

See a GP or get urgent assessment, so the symptom itself is looked at directly. Call 999 or go to A&E in an emergency.

Sources

• UK National Screening Committee. Principles of screening
• UK National Screening Committee. Ovarian cancer
• UK National Screening Committee. Recommendations (cancer)
• NICE. Suspected cancer: recognition and referral (NG12)
• NHS. PSA test
• NHS. Bowel cancer screening
• Cancer Research UK. Screening for ovarian cancer
• General Medical Council. Medical register, Mohammad Bakhtiar, 4694470

Written By

Stephen Lingam

Managing Director

Managing Director of Medical Express Clinic and the Health Screening Clinic since 1984. Over 40 years of operational experience in private healthcare on Harley Street, overseeing patient care, clinical standards, and service delivery.

Medically Reviewed

Dr Mohammad Bakhtiar

MD, PhD, LRCP, MSc, DHMSA

Clinical Lead

GMC: 4694470

Leading our clinical team with a focus on comprehensive men's health and preventative oncology protocols.

Last reviewed: 25/09/2026