Diagnosis and Prognosis of Melanoma
Diagnosis begins when you or a family member or your doctor notice a mole that has features which are concerning for melanoma. These features are listed below under Physical Exam. Any mole with these features should be brought to your doctor’s attention. A biopsy is necessary to determine whether a melanoma is present.
The diagnosis and prognosis of melanoma includes the following:
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.
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.
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 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 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.
The Staging Classification
The following stages are currently used to classify the stage of melanoma:
Stage 0 – the abnormal cells are found only in the outer layer of skin and do not invade deeper tissues.
Stage I – Melanomas up to 1 millimeter (mm) thick, or from 1–2 mm without ulceration. No spread to lymph nodes or other parts of the body.
Stage II – Melanomas from 1–2 mm with ulceration, and all melanomas greater than 2 mm. No spread to lymph nodes or other parts of the body.
Stage III – Melanomas of any depth, with spread to lymph nodes but not to other parts of the body.
Stage IV – Melanomas that have spread to other parts of the body, such as skin far away from the site of origin, internal organs, bones, brain, etc.
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%
National Cancer Institute
American Cancer Society
Bast, R., et al. Cancer Medicine e5 ., Hamilton, Ontario: B.C. Decker Inc.; 2000
Rakel, R. Conn's Current Therapy 2002 , 54th ed., St. Louis, MO: W. B. Saunders Company; 2002: 808-809.
Balch, et al., J Clin Oncol 2001; 19: 3637.
Last reviewed February 2003 by Donald Lawrence, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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