Diagnosis and Prognosis of Melanoma

Review of Medical History

The doctor will ask you about your symptoms and medical history. He or she will ask when you first noticed the change in your skin. You may be asked about sun exposure and the use of tanning booths.

Physical Exam

The doctor will perform a physical exam and carefully assess your skin and moles. He or she will look at the following:

• Moles that are larger in diameter than a pencil
• Moles that are asymmetric
• Mole borders that are irregular
• Moles of uneven color
• Moles that are changing (even shrinking) or bleeding

It is important to note that not all melanomas are black or brown. Some may be flesh-colored, blue, or red. Melanomas frequently arise in an area where there was a mole, but this is not always the case. The doctor may take a photograph of the lesion or other moles you have. If any of your moles look like they may be cancerous, the doctor may take a biopsy (tissue sample) and send it to a laboratory for testing.

The doctor may also examine lymph nodes in the groin, underarm, neck, or areas near the suspicious mole. Enlarged lymph nodes suggest that the melanoma may have spread beyond the mole.

Diagnostic Testing

If your doctor suspects one of your moles may be cancerous, he or she will do a skin biopsy. This is an office procedure involving the removal of all or part of the mole so it can be checked for cancer cells. The doctor will administer a local anesthesia. The biopsy can show whether or not there is cancer.

Cytology

Cytology is the study of cells. The cytology of cancer cells differs significantly from normal cells, and physicians use the unique cellular features seen on biopsy samples to determine the diagnosis and assess the prognosis of a cancer. A pathologist will examine the tissue sample under a microscope to check for cancer cells.

Staging Melanoma

Staging is the process by which physicians determine the prognosis of a cancer that has already been diagnosed. Staging is essential for making treatment decisions (e.g., surgery vs. chemotherapy). Several features of the cancer are used to arrive at a staging classification, the most common being the size of the original tumor, extent of local invasion, and spread to distant sites (metastasis). Low staging classifications (0–1) imply a favorable prognosis, whereas high staging classifications (4–5) imply an unfavorable prognosis.

Once melanoma is found, tests are performed to find out the thickness of the primary lesion and whether the cancer has spread and, if so, to what extent. This information helps your doctor determine which treatment is best for you. Melanoma, like other cancers, is classified according to stages.

Staging is an attempt to determine the extent of cancer invasion. It considers:

• The thickness of the tumor (measured using a microscope)
• If it has formed an ulcer (that is, whether the surface layers of skin have eroded, often accompanied by bleeding)
• The presence of cancer cells in local lymph nodes
• Whether the cancer has spread to other parts of the body and, if it has, what body parts are affected

Additional tests to determine staging may include:

• Urine and blood tests
• Chest x-rays – a series of standard x-ray images of your chest.
• Bone, liver, or brain scans – an injection of a radioactive compound called technetium is given. Three hours later, you lie on a table. Special cameras move slowly above and below the table taking pictures; these cameras detect small amounts of radioactivity in the injected technetium. This allows the doctor to see areas of the bone that may contain cancer cells.
• MRI scan – a test that uses magnetic waves to produce images of the inside of the body. Using a large magnet, radio waves, and a computer, an MRI produces two-dimensional and three-dimensional pictures.
• CT scan – a type of x-ray that uses a computer to produce cross-sectional images of the inside of the body
• Lymphoscintigraphy – a test to track the flow of lymph. It is performed prior to a sentinel lymph node biopsy, which is done to see if cancer has spread to the lymph nodes.
• Sentinel lymph node biopsy – is used when lesions are more than 1 millimeter (mm) deep. It is a method of checking if cancer cells have spread to the lymph nodes. A radioactive substance and a dye are injected near the tumor to help the doctor identify the sentinel node, which is the node where lymph first drains from the tumor area. The surgeon removes the sentinel node (or nodes). The sentinel lymph node (or nodes) is checked for cancer cells. If cancer cells are found, the surgeon removes the rest of the lymph nodes in that area. The lymph nodes are also taken out if the sentinel lymph node cannot be located. If cancer cells are not seen in the sentinel node, it is unlikely that the cancer has spread. The other lymph nodes are not removed.

Not all of these tests are appropriate or needed for every patient with melanoma.

Prognosis

Prognosis is a forecast of the probable course and/or outcome of a disease or condition. Prognosis is most often expressed as the percentage of patients who are expected to survive over five or ten years. Cancer prognosis is a notoriously inexact process. This is because the predictions are based on the experience of large groups of patients suffering from cancers at various stages. Using this information to predict the future of an individual patient is always imperfect and often flawed, but it is the only method available. Prognoses provided in this monograph and elsewhere should always be interpreted with this limitation in mind. They may or may not reflect your unique situation.

Ten-year survival rates by stage:

• Stage 0: 100%
• Stage 1: 79% to 88%
• Stage II: 32% to 64%
• Stage III: 15% to 63%
• Stage IV: 6% to 16%