When doctors suspect the spread of your primary cancer from one part of the body to the other (metastasis)—for example, from the breast or prostate to the bone, lungs or liver—they’ll typically order various body-imaging tests, like X-rays or MRIs. However, because no definitive test or examination can confirm metastasis, your doctor may order one or more of the following screenings:
Certain cancers release substances called tumor markers into your bloodstream, and blood tests are used to measure an increase in levels of these markers. A rise in levels may mean the cancer is progressing or has spread.
During an ultrasound, echoes from sound waves bounce off your organs and tissues to create images of your insides. An ultrasound is also helpful in distinguishing fluid-filled cysts from solid tumors, as the echo patterns are different.
How it’s done: A special gel that conducts sound waves is applied to the skin. A transducer, an instrument that produces sound waves, is rubbed over the gel.
Computed tomography (CT) scan
A CT scan, a type of imaging test, may be able to determine if the cancer has spread to areas such as the brain, lungs or liver. Because the CT scan rotates around your body, it creates multiple images of a tumor’s shape, size and location.
How it’s done: You’ll lie on a table that slides into the opening of the scanner; multiple X-rays will be taken from 10 to 30 minutes.
Magnetic resonance imaging (MRI)
MRI uses a powerful magnetic field, radio frequency pulses and a computer to produce detailed pictures of the body. Specifically, MRIs are used to identify cancer throughout the body or a certain area in question (they’re especially good for examining the brain and spine).
How it’s done: Similar to a CT scan, patients lie on a table that goes inside the MRI machine. Instead of X-rays, however, MRI uses radio waves and magnets to create cross-sectional images.
Positron emission tomography (PET) scan
PET scans monitor how your organs and tissue are functioning inside the body.
How it’s done: Before the scan, you’ll be injected with a tracer, a radioactive substance that moves through the body and becomes absorbed by the organ and tissue being examined. You’ll then lie on a table that moves into the PET machine, which detects energy given off by the tracer. The energy is converted into cross-sectional images of where the cancer may have spread in the body.
These scans look for abnormalities in the bones.
How it’s done: Like a PET scan, you’ll receive an injection of a tracer that circulates throughout the body, which usually takes several hours. A camera is then able to pick up “hot spots” that show up on the scan, which may suggest the presence of a tumor in the bone. However, bone diseases, fractures and infections can also cause “hot spots” to appear, so further testing may be needed to evaluate irregular bone scan results.