Can a blood test detect cancer?

A blood test cannot detect cancer in the way people hope it can. It can show metabolic risk, and some packages add tumour-marker clues. Those clues still need a doctor, an examination and, often, imaging. A raised marker is not a diagnosis. A normal marker is not an all-clear.

People land on this question because a tube of blood feels like the cleanest possible answer: one draw, one number, one verdict. The UK National Screening Committee describes screening as the process of 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 does not sit outside those limits.

What Essential bloods measure

At The Health Screening Clinic the Essential MOT is a doctor-led baseline at 117a Harley Street. The bloods in that tier are metabolic. They look at 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 liver or kidney strain. It is not a cancer screen.

A full blood count can sit outside range for infection, iron deficiency, medicines or other reasons that have nothing to do with a tumour. Raised cholesterol is a cardiovascular conversation. HbA1c is about glucose control. Those results still matter. They are a different job from asking whether you have cancer.

If that is the question you brought, Essential is the honest booking. It gives you a GP consultation, a physical examination and a reviewed metabolic panel. It does not add CEA, PSA or CA-125, and it should not be read as an oncology shortcut.

Why tumour markers are clues, not screens

Tumour markers are proteins that some cancers produce. Ordinary tissue can produce them as well. CEA, PSA and CA-125 sit in that group. They can be raised when there is no cancer. They can sit inside the laboratory range when cancer is present. That double failure is why they make a poor population screen, and 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 inside defined symptom-led pathways, not as a general all-clear. For persistent symptoms that suggest ovarian cancer, NICE recommends measuring CA125 in primary care and then arranging an ultrasound depending on the result. That is a route for people who already have symptoms. It is not a national ovarian screen. 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.

The same logic applies to prostate. NHS pages are plain that a high PSA does not mean you have cancer, and that it may be an enlarged prostate or other non-cancer change. Inflammation, infection, recent ejaculation, cycling and breathless exercise can lift the figure. A low or ordinary-looking result is not a lifetime all-clear either. Routine PSA testing is not currently offered on the NHS as a population programme, although men can discuss the test with a GP. The UK NSC still does not recommend population prostate screening.

CEA is used mainly in people already known to have bowel cancer, to watch for recurrence. It is not a bowel screen. Smoking, inflammatory bowel disease, liver disease and other adenocarcinomas can lift it. Early bowel cancer often leaves it normal. The NHS bowel programme uses a stool FIT kit, not a CEA blood test, for that reason.

Circulating-tumour-cell tests and other liquid biopsies are sometimes offered as a wider cancer blood test. The Health Screening Clinic offers one, Trucheck, as part of Whole Body Cancer Screening at £3,499. It is not part of any NHS programme and has not been shown to reduce cancer deaths. These tests are not an NHS all-clear. They are not a substitute for the breast, cervical and bowel programmes that already exist, and they do not replace imaging of a named organ. A private blood result that looks for tumour cells in circulation still needs clinical review, and it does not close the door.

What Elite and Ultimate add, and what they do not

Elite is the MOT that adds tumour markers, because it already includes the examination and imaging those markers would need if they flag.

Currently £1,850 for men and £2,095 for women, it includes CEA for everyone, PSA for men aged 40 and over, and CA-125 for women, alongside gender-specific ultrasound. Women also have a mammogram from 40, a smear and consultant gynaecology. That combination is the point. The marker is read with the pictures and the person on the couch, not as a lone number on a PDF.

Ultimate adds HE4 and a ROMA score for women, on top of CA-125, on the Ultimate Health MOT. Those extra ovarian markers can refine risk information when a doctor is already looking at pelvic imaging and history. They do not diagnose ovarian cancer and they do not exclude it. ROMA is a calculation that combines HE4, CA-125 and menopausal status. It is not a verdict.

Choose the Elite Health MOT when you want those markers inside a doctor-led assessment that already includes ultrasound and specialist input, not because a longer blood list sounds like a cancer screen. Essential remains the right booking if the question is a metabolic baseline rather than markers and imaging.

Why the MOT puts bloods next to examination and imaging

Laboratories mark results against a reference range. That range is a statistical interval, not a medical sentence. A flag means look again with the rest of the picture. It does not mean you have cancer. It does not mean you do not.

That is why every MOT at the clinic includes a GP consultation, a physical examination and an in-person review of the report. Blood numbers without an abdomen being examined, a prostate being considered, a breast being assessed, or a scan being read, leave you with a clue and no map. Imaging without bloods and examination leaves you with a picture and no chemistry. The packages exist because those pieces 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. If a marker is ordinary, the same doctor still has the examination and the imaging. New, severe or worsening symptoms still belong with a GP or urgent assessment rather than with a screening diary date. Use 999 or A&E for emergencies. A preventative package is built for people who feel well enough to be screened, not for an illness that is already unfolding.

When the question is a named organ

A MOT is a wide preventative assessment on the Health MOT menu. When the question is one organ, a named cancer-screening package is the better fit. It puts the right test in the room rather than hoping a general blood panel will stand in for it.

Prostate screening reads PSA against examination and, when the tier includes it, prostate MRI. CEA on its own cannot do that work. Breast screening uses a mammogram from 40, ultrasound or MRI according to age and density. There is no useful breast tumour marker that replaces those pictures. Bowel screening uses quantitative FIT and, when imaging is the issue, CT colonography. CEA is not the bowel test. Lung screening in people who have smoked uses low-dose CT. A metabolic blood panel will not see a small nodule.

Keep the NHS invitations you already receive. Breast, cervical and bowel programmes exist because those tests, in those age groups, have evidence behind them. A private MOT or a private organ package does not replace them. The UK NSC recommends those population programmes. It does not recommend a catch-all cancer blood test.

Tips and tricks

• Name the question before you book.
• Metabolic baseline is Essential.
• Markers plus gender-specific imaging is Elite.
• A named organ is an organ package.
• Say if cancer runs in the family, and bring previous bloods, smears, mammograms, PSA figures and clinic letters. The doctor is reading a trend and a body, not a single printout.
• Fast only if the clinic instructed you to for the tests you booked.
• Continue regular medicines unless you were told otherwise.
• For PSA, follow the 48-hour advice on the NHS page: no ejaculation, anal sex, breathless exercise or cycling, and wait four to six weeks after a urine infection has cleared.
• Keep NHS breast, cervical and bowel invitations even if you are booking privately.
• Leave room in the diary for the review appointment. That is when a flag becomes a plan.

Things to avoid

• Do not treat a tumour marker as a cancer screen, a diagnosis or an all-clear.
• Do not treat Essential metabolic bloods as oncology.
• Do not treat a circulating-tumour-cell test, including the Trucheck test this clinic offers, as proof that every tissue is clear.
• Do not book a screening MOT because you have a new lump, unexplained weight loss, coughing blood, a changing bowel habit, or anything else that is getting worse. That needs a GP or urgent pathway now.
• Do not shop a menu of extra markers as if collecting proteins were the same as screening an organ.
• Do not skip the examination or the review.
• Do not drop NHS programmes because a private package included a smear, a mammogram, a FIT or a PSA.

If you do want cancer screening that starts from the question rather than from a blood-test catalogue, the organ packages and the wider MOT sit on the cancer screening page, or you can contact The Health Screening Clinic on 020 7183 7056.

For what each marker in the Health MOT menu does, read tumour markers in a MOT. For a named organ, whole-body cancer screening versus an organ package sets out the difference.

Frequently asked questions

Can a blood test detect cancer?

No. A blood test can show metabolic risk and, in some packages, tumour-marker clues. Those clues still need examination and often imaging. A raised marker is not a diagnosis. A normal marker is not an all-clear.

Are the Essential MOT bloods a cancer screen?

No. Essential bloods are metabolic: blood count, kidney and liver function, lipids, glucose, thyroid, iron and related chemistry. They are a baseline, not oncology.

What do CEA, PSA and CA-125 show?

They are tumour-marker clues used inside the Elite MOT. NICE NG12 uses PSA and CA125 in symptom-led pathways, not as general cancer tests. Each can be raised for non-cancer reasons and normal with cancer.

Does a normal marker mean I do not have cancer?

No. Markers miss disease as well as over-flag it. The examination and any imaging in the package still have to be read.

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

When the question is a named organ: prostate, breast, bowel or lung. A MOT is a wide preventative assessment. An organ package puts the test that belongs to that organ in the room.

I have a new or worsening symptom. Should I book screening?

No. New, severe or worsening symptoms need a GP or urgent assessment, not a preventative package. Use 999 or A&E for emergencies.

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