There is no single definitive diagnostic test for cancer. Many tests and examinations are used to establish the diagnosis, as there are many kinds of cancer.1
The type of cancer, as well as the part(s) of the body it affects, will guide a doctor’s decisions about tests to order, as well as influence their choice of treatment.
Taking a person’s medical history, performing a physical exam, ordering blood and imaging tests, as well as biopsies, are all steps a doctor might take if they suspect someone has cancer.
Early detection significantly increases the likelihood of cancer being treated successfully.2
One proactive step you can take is performing regular self-checks at home. Cancers that you can do self-checks for include:
- Breast cancer. The breasts should be regularly examined for any changes in shape and texture.
- Testicular cancer. Regular checks of the testicles can detect changes in shape, size, or texture.
- Skin cancer: Changes on the surface of the skin (anywhere from the head to the toes) that could be skin cancer include new warts, moles, spots or lumps.
If you notice something concerning when doing a self-check, see your doctor. While changes in the breasts, testicles, and skin are often normal, your doctor can order the tests necessary to rule out cancer.
Labs and Tests
Your doctor can choose from an array of medical tests that can help them diagnose cancer. If you aren’t sure why you having a test, ask your doctor to explain why they have ordered it, or why they’ve chosen one test or scan over another.
Blood tests measure the levels of substances in your body, such as red blood cells, white blood cells, and markers of inflammation. While blood tests can help, they cannot definitively diagnosis cancer.3
A (CBC) and a blood chemistry profile are two of the most common blood tests, but your doctor may also order more specialized tests.
- Complete blood count. This test measures the number of blood cells, including circulating in your body. The test also measures hemoglobin and hematocrit levels. is an oxygen-carrying protein found in your red blood cells and in your blood as a whole. is the ratio of the volume of red blood cells to the total volume of blood. A complete blood count is particularly useful for diagnosing and monitoring cancers that affect the blood
- Blood chemistry profile. Sometimes called a chemistry panel or metabolic profile, this test measures levels of fats, electrolytes, enzymes, hormones, and proteins in the body. The levels of these substances help a doctor see how well organs are functioning. For example, measure proteins likeand enzymes like The levels of these proteins and enzymes indicate how well your liver is working.
- Cytogenetic analysis. This test looks at to see if there are changes in the number or structure of the cells’ chromosomes. Alternatively, cells may also be examined.
examines the appearance and contents of your urine for signs that may indicate cancer. Examining urine can help diagnose kidney and urothelial cancers (which affect the ureters, urethra, and renal pelvis).4
To confirm a cancer diagnosis, your doctor will surgically remove some tissue or cells from the tumor in your body and send the sample to a lab for testing.
There are many types of biopsies. The one your doctor performs will depend on the type of cancer suspected and where the tumor is located.
- Fine needle aspiration (FNA). A small, thin, and hollow needle is used to remove cells and a little fluid from a tumor. If the tumor is deep within the body, an ultrasound or CT scan will be used to guide the needle.
- Core biopsy. The needle used for a core biopsy is slightly larger than for FNA, but the procedure is similar. It’s performed with local anesthesia to help reduce pain.
- Excisional biopsy. A surgical procedure where the skin is cut and the entire tumor is taken out. The area is numbed with If the tumor is deeper in the body (such as in the stomach or chest) is used. Sometimes, the doctor may also remove some of the normal tissue surrounding the tumor.
- Incisional biopsy. A surgical procedure similar to an excisional biopsy, except that only a small part of the tumor is removed (rather than taking it all out).
- Endoscopic biopsy. A flexible, slim tube with a camera and light attached to one end is inserted into a specific part of the body, such as the mouth, nose, throat, bladder, and lungs. During the procedure, medical tools can be passed down through the tube to allow the doctor to remove cells or samples of tissue.
- Laparoscopic biopsy. Similar to the endoscopic biopsy, this biopsy uses an instrument called to see inside the abdomen and obtain tissue samples.
- Skin biopsy. Your doctor can select from different depending on the type of skin cancer they suspect. A punch biopsy removes a sample of the deep layers of the skin A shave biopsy removes the uppermost layers of the skin (the epidermis and part of the dermis). This test is suitable for diagnosing some types of basal cell or squamous cell skin cancers. Incisional skin biopsies remove parts of the skin down to the Excisional biopsies remove the entire tumor. Skin biopsies are performed using local anesthesia to numb the area.
Cytology tests look for cancerous cells in bodily fluids.6 Examples of body fluids cytology tests can be carried out on include:
- Urine(phlegm or mucus from the lungs)
- (in the space around the lungs)
- (in the sac surrounding the heart)
- (in the spaces around the brain and spinal cord)
- Ascitic or (in the abdominal cavity)
Cytology tests can also be performed on cells scraped or brushed from a particular organ. This is called scrape or brush cytology.
A well-known example of this technique is a which looks for abnormal cells in cervical tissue. The mouth, esophagus, bronchi, and stomach can also be scraped and brushed for cells.
After you’ve been diagnosed, your doctor may order tumor marker tests and genetic tests to determine the exact type of cancer you have, assess its stage, and decide on treatment.
Anxiety and Cancer Testing
If you need tests to find out if you have cancer, it’s normal to be anxious and upset. Look to your loved ones for support and know that even if the test confirms the diagnosis, many cancers can be treated (especially if they’re found early).
Imaging tests let a doctor obtain images of the internal parts and organs of your body. These pictures help them see if there are tumors or changes that could be caused by cancer.7
are fast, painless tests that use low doses of radiation to obtain images of different parts of your body. In some cases, a special is given to make the pictures show up clearer. The dye may be given to you to swallow, injected into your veins, or passed to your intestine through your rectum.
Computed Tomography (CT) Scan
(CT) scan uses an X-ray machine connected to a computer to take several pictures of your body from different angles, then processes them into cross-sectional images.
Like with regular X-rays, a special contrast dye may be given to you to make the pictures clearer or help your doctor see a specific organ or structure better.
This scan involves the use of high-frequency sound waves to generate images known as sonograms. Ultrasounds can help diagnose cancers located in areas that don’t show up clearly on X-rays.8
Ultrasounds can also help doctors guide needles during core biopsies.
Magnetic Resonance Imaging (MRI) Scan
Like CT scans, creates cross-sectional images of your body. Instead of using X-rays, MRIs use magnetic fields and radio waves to create high-resolution pictures.
MRIs can also help determine whether cancer has spread to other parts of the body.
Breast cancer can be detected with a type of X-ray called mammograms.9 machines are specifically designed to examine breast tissue for abnormalities.
Before having a mammogram or any other type of X-ray, let your doctor know if there’s Depending on the area of your body that needs to be X-rayed, you may need to take special precautions to avoid or reduce fetal exposure to radiation.
Nuclear Medicine Scans
These tests help doctors find tumors and correctly stage cancers. These tests use radionuclides (substances which you swallow, inhale, or are injected with) that give off small doses of radiation.10
The radionuclide, also called a tracer, accumulates in your body. With the aid of special cameras and computers, your doctor can obtain 2D and 3D images of the part of the body being tested.
For endoscopic procedures, a doctor inserts a tube-like device into your body so they can see inside. The tube, called an endoscope, has a light and small camera attached to its end.
used to diagnose cancer include:
- Upper endoscopy
Screening tests help detect cancer before a person has any signs or symptoms.11
There are reliable screening methods for many, but not all, types of cancer.
People at may need to be screened regularly. For people who don’t have specific risk factors, routine screenings for specific cancers may be recommended once they reach a certain age.
According to CDC data, screening tests can help prevent deaths from certain types of cancer through early detection.12
can be screened in the following ways.
- Mammogram. A type of x-ray designed specifically for breasts. The scan can show tumors and detect irregularities.
- Self-examination. Checking your own breasts at home for changes in shape or size.
- Physical examination by a physician. Your doctor looks at and physically examines your breasts and nipples.
- Breast MRI. A type of MRI designed specifically to detect breast tumors.
There are several tests and procedures used to screen for cancer of the colon and rectum, including:
- Colonoscopy and sigmoidoscopy. A tube with a camera is inserted into the anus to allow a doctor to see inside the
- Stool DNA test. Analysis of your stool for DNA changes typical or cancer.
- Double-contrast barium enema. An X-ray of the colon and rectum, in which is used as a contrast agent to make the colorectal area show up more clearly.
- Fecal occult blood test (FOBT). Detects tiny traces of which can be a sign of colorectal polyps or cancer.
- Pap smear. The collection of through scraping, to check for abnormal cell changes.
- HPV test. Similar to a Pap smear, but strains of (HPV)—a sexually transmitted infection that strongly increases a woman’s risk of —are also checked for. Your doctor may only recommend and if your pap smear results are abnormal.
According to the Centers for Disease Control and Prevention guidelines, most people with a prostate should start talking to their doctor about routine screenings by the age of 55.13
- Digital rectal examination. A doctor inserts a gloved finger into your rectum to for any abnormalities.
- Prostate-specific antigen (PSA) test. A blood test that measures the level of the in your body. Higher than normal levels may indicate prostate cancer.
People who are high-risk for prostate cancer may be advised to begin regular screenings at a younger age.
It’s a good idea to get in the habit of checking your skin for changes, but the CDC doesn’t recommend regular skin cancer screenings for people without specific risk factors.14
However, if you’ve had before or have a skin change (such as a new mole) that needs to be monitored, it’s important to regularly check in with your doctor.
- Physical examination. Your doctor will look at and touch your skin to look for signs of skin cancer.
- Dermoscopy. With the aid of a medical instrument called a dermatoscopy, your doctor will look more closely at any pigmented skin lesions on your body. The exam is particularly useful for catching early.15
Drawbacks of Screening Tests
There are risks and drawbacks of screening tests. Some cancers grow slowly and will not cause any symptoms or illness in your lifetime. In these cases, screenings can lead to “overdiagnosis” and medical care you don’t need.16
While screening tests can help diagnose cancer, they are not perfect. Sometimes, the tests do not detect cancer that is present. Other times, the results of the test indicate someone has cancer when they do not. are a risk of any cancer screening.17
Inaccurate cancer test results are extremely stressful and can also be a financial burden. For example, the cost of pursuing more diagnostic tests when they are not actually necessary.
If you regularly do self-checks at home and are concerned about cancer, talk to your doctor. They will be able to help you understand your risk, as well as the risks of the test used to diagnosis cancer. Together, you can decide which screening tests are right for you, and when you should begin having them.