Doctors use many tests to diagnose cancer and find out if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of cancer, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:
- Age and medical condition
- Type of cancer suspected
- Severity of symptoms
- Previous test results
In addition to a physical examination, the following tests may be used to diagnose eyelid cancer:
Biopsy . Because basal cell and squamous cell cancers rarely spread to other parts of the body, a biopsy is often the only test needed to determine the extent of cancer. A biopsy removes a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The type of biopsy performed will depend on the location of the cancer. During this procedure, performed under local (numbing) or general anesthetic, the doctor removes the suspicious tissue using techniques that test the thickness of the cancer and its margins (healthy tissue around the lesion). The tissue sample is sent to a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease) who determines if the sample contains cancer and, if so, which type. The amount of normal tissue removed around the cancer depends on its thickness. Further treatment beyond the biopsy may not be necessary if the entire growth is removed. If cancer is present at the edges of the tissue taken for the biopsy, additional treatment (for example, surgery, radiation therapy, or cryotherapy; see Treatment ) is usually necessary.
Computed tomography (CT or CAT) scan . A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a patient's vein to provide better detail.
Magnetic resonance imaging (MRI) . An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium (a special dye) may be injected into a patient's vein to create a clearer picture.
Positron emission tomography (PET) scan . A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient's body. This substance is absorbed mainly by organs and tissues that produce the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body.
Ultrasound . An ultrasound uses sound waves to create a picture of the internal organs.
To plan treatment, the doctor will determine the extent, or stage, of the cancer. The stage depends on how thick or large the tumor is and whether there is evidence that the cancer may have spread. Occasionally, a patient's lymph nodes may be removed to determine if the cancer has metastasized. The doctor may perform other tests, including blood sample analysis, MRI, and diagnostic scans of the liver, bones, and brain. Read Staging and Grading  for more information.
Learn more about what to expect when having common tests, procedures, and scans .
After these diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer; this is called staging . Learn more about the first steps to take after a diagnosis of cancer .