How is cancer diagnosed?
Diagnosing cancer is a complex process and there's no one best way to do this. Every person is different, and there are many different kinds of cancer that can cause a lot of different symptoms.
If your healthcare provider thinks you have cancer, a complete work-up will be done. It will likely include a physical exam, asking you about your health history and symptoms, a review of your family history of illness, blood tests, special procedures, and/or imaging tests. Many times, a tiny piece (sample) of the changed cells or tumor must be taken out and tested. This is called a biopsy. Sometimes it's the only way to know for sure that you have cancer.
Once a cancer is found, more imaging tests might be done to see if and how far the cancer may have grown or spread. This process is called staging. All of this information is used to make the treatment plan that's best for each person.
What are the different types of diagnostic imaging used for cancer?
Imaging is used to make pictures of the inside of your body. It can help find tumors and other changes, show how much disease is there, and help see if treatment is working. Imaging may also be used to do biopsies and other surgical procedures.
Here are some of the common imaging tests that may be used for cancer.
X-rays use low doses of radiation to make images of your tissues, bones, and organs. X-rays may be taken of any part of the body to look for a tumor or cancer.
This scan uses X-rays and a computer to make 3-D images (often called slices) of your body. A CT scan can show any part of your body, including bones, muscles, fat, and organs. CT scans are a lot more detailed than X-rays.
A mammogram is an X-ray exam of the breast. It's used to find and diagnose breast disease in people who have breast problems, such as a lump, pain, or nipple discharge. It's also used to check for breast diseases in women who don't have breast problems. (This is called a screening mammogram.)
A mammogram can’t prove that a breast change is cancer. But if it shows something that might be cancer, more testing can be done.
Ultrasound uses high-energy sound waves and a computer to make images of blood vessels, tissues, and organs. It can be used to look at how well organs are working and to look at blood flow through vessels. Tumors in the belly (abdomen), liver, and kidneys can often be seen with an ultrasound. (It's not useful in the chest because the ribs block the sound waves.)
Ultrasound can also be used through a probe that can be put into body openings, like the anus, vagina, or esophagus. This puts it closer to the certain internal organs, which can give a clearer picture.
MRI uses a strong magnet, radio waves, and a computer to make detailed images of organs and other structures inside your body. An MRI is often used to look at the heart, brain, liver, pancreas, male and female reproductive organs, and other soft tissues. MRI can show even small changes in tissues. It can assess blood flow, find tumors, and diagnose many forms of cancer, evaluate infections, and assess injuries to bones and joints.
PET scan (positron emission tomography scan)
A PET scan can show differences in the activity of the tissues in your body. It uses a tiny amount of a radioactive substance attached to a sugar. (This is called a radionuclide or a radiopharmaceutical or radioactive tracer.) The tracer is put into your blood. Over an hour or so, it collects in super-active cells, like cancer cells. Then a special scanner is used to see where the tracer has collected in your body.
PET and CT scans are often done together. This is called a PET/CT. It gives detailed images of the structure of your insides along with information about the activity of the cells and tissues.
Nuclear medicine scan
These scanners take pictures after a radioactive tracer (called a radionuclide) is put into your blood. This type of scan may also be called a radionuclide scan.
The scanner creates pictures that show where the tracer travels and collects. These spots might be tumors or other tissue damage. Some common nuclear scans are bone scans, PET scans, thyroid scans, and gallium scans. The type of scan done depends on which part of the body your healthcare provider wants to look at.