The idea of a single blood test for cancer is revolutionary, and such a test could potentially lead to earlier diagnosis. However, the reality is that there is no reliable blood test for cancer yet.
Cancer is one of the leading causes of death. The American Cancer Society estimates that cancer will be responsible for more than 600,000 deaths in the United States in 2021. The best outcomes typically occur when doctors find and treat cancer early.
Regular self-checks and screenings are an essential part of early cancer detection. Anyone who notices any abnormalities, such as lumps or skin dimpling, should consult a doctor as soon as possible. Rather than performing a single test, the doctor will use various diagnostic methods to look for cancer, such as:
In this article, we examine the routine blood tests that doctors use to detect cancer. We also look at whether people can test for cancer at home and suggest some questions that people can ask doctors if they have concerns about cancer.
Doctors can use blood tests to help detect cancer, but no single test can accurately diagnose it.
Routine blood tests are essential to determine a baseline for each person. Doctors can compare subsequent blood tests against this baseline and determine whether any results are abnormal.
Historically, doctors have needed to use multiple blood tests to diagnose cancer and other conditions that produce similar symptoms. However, scientists are researching the effectiveness of a single blood test.
Clinical trials are validating tests that could detect multiple types of cancer from a single blood draw, including the CancerSEEK assay, Galleri test, and PanSeer assay.
Doctors perform a complete blood count (CBC) to test blood. A CBC measures the number of red blood cells, white blood cells, and platelets in a blood sample.
CBC results that are above or below normal ranges may signify a health problem. Doctors also look for any biomarkers that could indicate cancer activity.
Finally, doctors examine the various chemicals in the blood, such as:
Checking these chemicals can help them evaluate the functioning of specific organs, including the:
A higher level of some blood proteins may signify disease severity by indicating the faster growth rate and larger size of a tumor.
Blood test results are not conclusive, as they can sometimes provide a false reading. For this reason, doctors order additional tests, such as imaging and biopsies, to back up blood test results.
In addition to blood tests, doctors may use other tests to diagnose cancer, including:
- tumor biopsies
- laboratory tests
- endoscopic examination
- physical examinations
Doctors use imaging to detect tumors and other abnormalities, evaluate the extent of the disease, and check whether someone’s treatment is effective.
Imaging technologies include:
Tumor biopsies involve removing tissue or cells from the body to analyze under a microscope. Doctors take a biopsy to determine whether a tumor is benign or malignant.
Standard biopsies include a bone marrow biopsy, endoscopic biopsy, and skin biopsy.
The most common lab tests use chemical processes to determine the levels of chemical components in tissues and bodily fluids, such as blood and urine samples. Doctors may check:
- blood glucose
It is not possible to perform a blood test for cancer at home. Extracting and analyzing blood requires clinic and lab facilities. However, the
One of these tests is a screening for colon cancer. A healthcare professional provides a test kit to use at home for stool collection. The person then sends the sample to a lab for analysis. The lab contacts the individual if the results are abnormal and they need to visit a doctor for additional testing.
There is no specific test that diagnoses cancer at home with complete certainty. However, people can use self-checks to help spot any changes or abnormalities as early as possible.
Anyone who notices anything unusual during a self-check should speak with a doctor as soon as possible.
Performing regular breast self-exams can assist in diagnosing breast cancer early. People should complete the following steps for a breast self-exam:
- Look at the breasts in the mirror while placing the hands on the hips and keeping the shoulders straight.
- Check that the breasts are their usual shape, size, and color and that there are no signs of puckering, dimpling, or bulging of the skin. Make sure that neither nipple has changed position or become inverted and that there is no soreness, skin discoloration, swelling, or rash.
- Raise the arms and look for the same changes.
- Look for any fluid coming out of the nipples.
- Lie down and feel the entire breast from top to bottom and side to side using a circular motion. Examine the whole breast, from the collarbone to the top of the abdomen and from the armpit to the body’s center.
- Perform the same checks as in the step above but standing up.
A self-examination of the testes can help detect testicular cancer early, so individuals should complete a self-exam monthly so that they can compare the findings over time. There are four steps to a testicular self-exam:
- Roll each testicle in one hand gently and examine it.
- Locate the epididymis, the soft tube-like structure behind the testicle. Becoming familiar with its location can help avoid accidentally mistaking it as an abnormal mass.
- Look for any lumps or irregularities.
- Look for changes in shape, size, or texture.
Skin cancer is another form of cancer that individuals can help diagnose early by completing self-checks.
When performing a skin self-check, a person must look at every part of the skin, even the bottom of the feet and armpits. People can use a mirror to check hard-to-see areas.
During a skin self-exam, people should look out for:
- a sore that is not healing after a few weeks
- a new, changing, or expanding spot, growth, or bump
- a scaly or rough discolored patch
- a wart-like growth
- a mole that is new or changing in shape, size, or color
- a mole with irregular borders, an odd shape, or a mix of colors
If someone finds irregularities when performing a self-exam, they should bring it to a doctor’s attention.
Below are some questions that people may find helpful to ask a doctor:
- Is this bump, lump, or mole abnormal?
- Do I need any additional tests to determine whether it is cancerous?
- What tests do I need?
- What is the next step?
If a blood test comes back showing markers for cancer, questions that a person can ask include:
- Is there a chance that it was a false positive?
- What tests should I have next?
- Do I need only one test or multiple tests?
- At what point will I know for sure whether it is cancerous?
- Will I need to monitor this if it ends up being a false positive?
Although there is no single test that can detect cancer in the body, doctors do use several blood tests to diagnose cancer. They use these alongside other methods, which include imaging, chemical analysis, and biopsies.
Researchers are working on developing new tests that may provide novel ways to detect cancer in blood samples.
Individuals cannot self-diagnose cancer at home, but they can perform regular self-exams to help detect problems as early as possible.
Breast, testicular, and skin self-exams are easy to complete, and they enable people to recognize abnormalities. People can notify doctors of anything unusual, such as moles, bumps, or lumps, so that they can provide additional testing.
People should complete self-exams regularly to establish a baseline for comparison.