Cancer is an uncontrolled growth of cells in the body. Diagnostic tests used to detect cancer vary depending on the type of cancer. So a test your doctor orders to diagnose pancreatic cancer may not be the same one they may use to diagnose blood cancer. If your doctor attempts to detect cancer before symptoms appear, they may use a cancer screening test.
Below are a few common tests used to diagnose cancer and assess overall health.
What types of tests are used to detect cancer?
Blood tests can test for different substances in the blood that may indicate the presence of cancer (tumor markers). Examples of blood tests include:
- Complete blood count: A complete blood count (CBC) measures the number of red blood cells, white blood cells and platelets in the blood.
- Urea and electrolytes: These tests show how well the kidneys are working. They also check for electrolytes (such as sodium, potassium, chloride and bicarbonate).
- Liver function tests (LFTs): These tests check how well the liver is working. LFTs look for levels of enzymes and proteins made by the liver or that are cleared by the liver.
- Tumor markers: Tumor markers are substances that may show in increased levels if cancer is present. They are usually proteins, and can be found in the blood, urine or body tissues. Some tumor markers are only produced by one type of cancer, while others can be produced by several types of cancers. Markers can sometimes be found in noncancerous conditions as well. If a patient has cancer, tumor markers can be used to diagnose the disease, monitor how well cancer treatment is working or check if the cancer has come back (relapse).
X-rays help doctors look for cancer in various areas in the body, including the kidneys, stomach and bones. X-rays are generally quick, painless and do not require any special preparation.
In special types of X-ray tests, contrast dyes may be used. Contrast materials (such as barium, an iodine-based dye) combined with X-rays may obtain better images for cancer detection.
Computed tomography (CT) scan
During a CT scan, X-rays are used to take images of the inside of the body from various angles. Then, a computer combines the pictures into a three-dimensional, detailed image that can help to reveal any tumors or abnormalities. In some cases, doctors may use a specialized dye called contrast medium, which is administered to the patient before taking the images. This dye helps provide better image detail.
A total-body CT scan typically includes at least the abdomen, chest and pelvis and is usually done for cancer staging. Common scanned areas include:
An MRI scan uses powerful radio waves and magnets to generate computer-generated, detailed images of the body. Doctors also use MRI scans to measure tumor size.
An MRI doesn’t use X-rays or other types of radiation. Because of this, physicians often use MRI scans when looking for issues in male and female reproductive systems. MRIs are typically safe, even for pregnant patients. Doctors also use MRIs to take pictures of the spinal column, brain, chest, abdomen and breast.
Ultrasound, ultrasonography or sonography
An ultrasound creates images of internal organs using high-frequency sound waves. These sound waves hit the organs, bouncing back to a device called a transducer. The transducer takes the sound waves and turns them into pictures shown on a computer.
The sound waves echo uniquely when bouncing off healthy and abnormal tissue, helping doctors detect possible tumors. There is no X-ray exposure in ultrasound tests, which means they are safe for pregnant women.
Positron emission tomography and computed tomography (PET-CT) scans
Doctors can combine PET scans with CT scans as an effective imaging test for finding cancer and detecting its stage. This type of scan may help your doctor to start the best treatment as early as possible. With a PET scan, they may even be able to predict the chances of recovery.
Mammography is a type of X-ray that doctors use to check for breast cancer. Mammograms produce images that may show tumors that can’t be felt during physical examination. Mammograms can also reveal other breast irregularities.
Nuclear medicine scans for cancer
Nuclear medicine scans generate images based on the body’s chemistry, unlike other imaging tests that are based on physical forms and shapes. The scans use liquid substances known as radionuclides, radiopharmaceuticals or tracers that release low radiation levels.
Body tissues affected by some diseases, such as cancer, may absorb more or less of the tracer than normal tissues. Specific cameras capture the radioactivity pattern and generate images that show the doctor where the tracer travels as well as where it is getting collected.
If cancer is present, the tumor may show up on the image as a hot spot. The tumor may also show up as a cold spot depending on what type of scan your doctor performs. A cold spot is the area of less cell activity or decreased uptake. Your doctor will determine the type of nuclear scan you will receive, depending on the organ they wish to investigate. Common nuclear scans used for cancer include:
- Bone scans
- Gallium scans
- Multigated acquisition scans
- Thyroid scans
Nuclear scans may not identify tiny tumors and can’t always indicate whether a tumor is cancer.
Annual checkups are an important protection for overall health, including safeguarding against cancer.
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