Blood tests primarily help detect blood cancers (leukemia, lymphoma, myeloma) through abnormal cell counts (CBC) or specific proteins, but for solid tumors (breast, lung, colon), they usually find tumor markers (like PSA for prostate, CA-125 for ovarian) or circulating DNA, serving as indicators that need further tests (biopsy, imaging) for definitive diagnosis. Newer liquid biopsy tests show promise for early detection of several solid cancers like stomach, lung, and liver, but are still developing.
Tumour marker blood tests
Tumour markers are substances that might be raised if there is a cancer. They're usually proteins. They can be found in the blood, urine or body tissues. You might also hear them called biomarkers or molecular markers.
Aside from leukemia, most cancers cannot be detected in routine blood work, such as a CBC test. However, specific blood tests are designed to identify tumor markers, which are chemicals and proteins that may be found in the blood in higher quantities than normal when cancer is present.
A CBC can detect some blood or immune system cancers like leukemia and lymphoma. But it can't detect solid organ cancers like lung, breast or colon cancers.
What's the hardest cancer to detect? Pancreatic cancer is often considered one of the hardest cancers to detect early.
Twenty potential signs of cancer include **unexplained weight loss, persistent fatigue, unusual lumps or swelling, skin changes (sores that don't heal, new moles, color changes), changes in bowel/bladder habits, persistent cough or shortness of breath, hoarseness/voice changes, difficulty swallowing, persistent indigestion, unexplained pain, night sweats, unusual bleeding/bruising, mouth sores that won't heal, loss of appetite, fever, changes in vision/headaches, swelling in lymph nodes, nipple changes, painful urination/ejaculation, and swelling in the face/neck; these warrant a doctor's visit if they last more than a few weeks.
Just as an abnormal result doesn't necessarily mean you have cancer, test results that come back normal don't guarantee that you don't. Most cancers are not yet detectable through blood testing. Blood tests should be seen as one part of an overall screening for potential cancer.
However, despite their invaluable role in cancer detection, general practitioners typically don't offer official cancer diagnoses. Instead, if cancer is suspected, your PCP will send you to a cancer specialist for more advanced care. This written order to receive care from an oncologist is called a referral.
The Galleri test, made by American pharmaceutical firm Grail, can detect fragments of cancerous DNA that have broken off a tumour and are circulating in the blood. It is currently being trialled by the NHS.
A full blood count (FBC) is a common blood test that measures different cells in your blood, including red blood cells, white blood cells and platelets. An FBC can help diagnose infections, blood disorders and clotting problems. If your results are higher or lower than usual, it doesn't always mean there is a problem.
Signatera is a custom-designed test that is generated based on each patient's unique set of tumor mutations. Knowing earlier if your cancer is likely to recur or has progressed after treatment can help you have a more informed discussion with your doctor on how to continue to treat or to detect changes in your disease.
During a physical exam, your doctor may look for abnormalities, such as changes in skin color or enlargement of an organ, that may indicate the presence of cancer. Laboratory tests. Laboratory tests, such as urine and blood tests, may help your doctor identify abnormalities that can be caused by cancer.
Blood tests already include a platelet count as standard – and a high platelet count can sometimes be an indicator of certain types of cancer, including lung and bowel cancers. Levels of platelets vary depending on age, and whether a person is male or female.
The blood tests have potential to screen for cancers, find them early and give patients a much greater chance of being cured. This has been made possible by a simple blood test that can not only detect more than 50 types of cancer, but also pinpoint where it's coming from with striking accuracy.
“Generally, most patients will have basic blood tests such as the Complete Blood Count (CBC), Complete Metabolic Panel (CMP), some tumor markers specific to the suspected cancer and CT scans,” explains Dr. Araoye. “Additional imaging may be required if more detailed information is needed.”
The 7 key warning signs of cancer often include changes in bowel/bladder habits, a sore that won't heal, unusual bleeding/discharge, a lump or thickening, persistent indigestion/difficulty swallowing, changes in moles, and a nagging cough or hoarseness, though many symptoms can overlap, so persistent changes warrant a doctor visit. These signs, especially when lasting over a couple of weeks, suggest a need for medical evaluation to rule out serious conditions, notes the American Cancer Society and Mayo Clinic.
An urgent referral can be worrying. But remember that more than 9 in every 10 people (more than 90%) referred this way will not have a diagnosis of cancer. In England, an urgent referral used to mean that you should see a specialist within 2 weeks.
Possible symptoms of cancer
A person with cancer can develop a low WBC count from the cancer or from treatment for the cancer. Cancer may be in the bone marrow, causing fewer neutrophils to be made. The WBC count can also go down when cancer is treated with chemotherapy medicines, which slow bone marrow production of healthy WBCs.
Like fatigue, cancer fatigue is whole-body exhaustion that you feel no matter how much sleep or rest you get. Cancer fatigue takes exhaustion a step further: You feel physically, emotionally and mentally exhausted most of the time. Cancer fatigue may last a few weeks (acute) or for months or years (chronic).
Low blood counts can have many causes, including vitamin deficiencies, bleeding, and rare bone marrow failure diseases like aplastic anemia, MDS and PNH. If your blood tests are abnormal, your doctor may do other blood tests or take a sample of your bone marrow.
Some general signs and symptoms associated with, but not specific to, cancer, include: Fatigue. Lump or area of thickening that can be felt under the skin. Weight changes, including unintended loss or gain.
About 90% of cancers are caused by environmental and lifestyle factors, not genetics, including smoking, poor diet (red meat, fried foods), alcohol, sun exposure, pollutants, infections, obesity, and inactivity; only 5–10% are due to inherited genetic defects, with most cancers arising from lifestyle-induced genetic mutations. Tobacco alone accounts for about a third of cancer deaths, while diet, obesity, and inactivity contribute significantly, with controllable factors being key to prevention.
The top 3 "worst" cancers, often defined by the highest number of deaths globally, are consistently lung cancer, colorectal cancer, and liver cancer, according to the World Health Organization (WHO) and other health organizations, with pancreatic cancer also frequently cited as extremely deadly due to poor survival rates. Lung cancer causes the most fatalities worldwide, followed by colon/rectum and liver cancers, though specific rankings can vary slightly by year and region.
Circulating tumor cell tests detect cancer cells in your blood. The cells might be in the blood if they've broken away from where they started and are spreading to other parts of the body. Circulating tumor cell tests are mostly used after a cancer diagnosis.