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• Highlights
• Introduction
• Other Skin Cancers
• Causes
• Risk Factors
• Prognosis
• Prevention
• Diagnosis
• Treatment for Melanoma
• Treatment for Other Skin Cancers
• Resources
• References

Melanoma and other skin cancers

Description

An in-depth report on the causes, diagnosis, treatment, and prevention of melanoma.

Alternative Names

Skin cancer; Squamous cell cancer; Basal cell cancer; Actinic keratosis

Diagnosis

An experienced doctor should first rule out benign conditions that resemble melanoma, such as a noncancerous mole called a melanocytic nevi. In rare instances, a melanoma will be difficult to detect. For example, an uncommon form of melanomas called a myxoid melanoma may be mistaken for a benign skin disorder known as a myxoid fibrohistiocytic lesion. Another opinion from a second pathologist, computerized image processing, or advanced staining techniques may help to confirm the diagnosis.

Some doctors now employ dermoscopy (also called dermatoscopy or epiluminescence microscopy), which uses a hand-held scope-like device that enhances the suspected lesion. It is still not clear if such devices are any better than the naked eye of a trained professional. Of interest, however, was a 2002 study suggesting that it was very useful in identifying possible melanomas in suspicious nail abnormalities and therefore avoiding many painful biopsies in this area. A 2004 study confirmed that adding dermoscopy to conventional naked-eye examination leads to fewer biopsies than using naked-eye examination alone.

A recently developed Australian device (the Solarscan) may improve detection. It is shaped like a hair dryer and takes an image of the suspicious lesion; it then reads the image and compares it with a databank of melanoma images to help determine if it is cancerous. It can also store the image of the lesion and compare it for changes with later images taken at subsequent check ups.

Biopsy

Biopsy of the Melanoma. Melanoma is diagnosed by biopsy (excision) of suspicious lesions. With this procedure, the doctor will anesthetize the area around the lesion and, depending on size and site, remove all or part of it. The biopsy specimen will be sent to a lab for analysis, where a pathologist will take thin slices of the lesion and examine the cell structure under a microscope. If melanoma is found, it will be staged and its depth and probability of spreading will be assessed.

• Melanomas less than 4 mm thick suggest Stage I or II cancers, and the next step is to attempt to determine if they have spread or are likely to spread to the lymph nodes.
• Melanomas that are over 4 mm thick indicated later stages. In such cases, the lymph nodes are sometimes removed to attempt to prevent the cancer from spreading, although about 70% of these melanomas have already metastasized (spread).

Sentinel Lymph Node (SLN) Biopsy. When Stage I and II melanomas metastasize, they most often spread first to nearby lymph nodes. A procedure called sentinel lymph node (SLN) biopsy helps determine whether lymph nodes might be involved and how far it may have spread. SLN biopsy is now recommended for cancers that are thicker than 1 mm (millimeter) and generally unnecessary for those thinner than 0.75 mm (unless they are ulcerated). Although some evidence suggests this procedure may improve survival, no clinical trials have proven to date that this procedure improves the prognosis in melanoma.

This procedure involves the following:

• A tiny amount of a tracer, either a radioactively labeled substance (radioisotope) or a blue dye, is injected into the tumor site.
• These substances then flow via the lymphatic system into the so-called sentinel node . This is the first lymph node to which any cancer would spread.
• The sentinel lymph node and possibly one or two others are then removed and biopsied.

The results of the biopsy can help doctors decide whether to remove other lymph nodes or not. The choices are not always clear cut, however:

• If the sentinel node and others shows signs of cancer then the nearby lymph nodes are removed.
• If they do not, particularly in Stage I, then it is highly likely that the remainder of the lymph nodes will be cancer free, and further surgery becomes unnecessary.

Controversy exists over the best approach for patients with Stage II cancers when the sentinel node test has found no evidence of cancer. These melanomas are usually between 1 mm and 4 mm thick, and tumors at this stage carry a risk for sending microscopic cancer cells out into the lymph system unnoticed. However, new methods of examining sentinel lymph node biopsies are improving the ability to identify these cells, called micrometastases. Still, in such cases, removal of lymph nodes would probably have no impact on survival.

Biologic markers in blood tests may also prove to identify microscopic cancers if sentinel node biopsy results are uncertain.

Secondary Tests

If melanoma has been diagnosed, the doctor will perform others tests to see if the cancer has spread. They typically include the following:

• A chest x-ray.
• Blood tests that show high levels of lactate dehydrogenase suggest metastasis.
• Blood tests to assess liver function and other factors to help determine specific sites where the cancer may have spread.
• Advanced imaging techniques, such as computed tomography (CT) or positron emission tomography (PET), may also be used. PET is particularly accurate. One study reported that PET was able to diagnose melanoma that had spread even when other tests, including CT, did not. PET can also be very accurate for identifying recurrent melanomas.

Biologic Markers for Metastasis

Researchers are continually looking for other biologic factors, or markers, that would indicate whether the cancer had metastasized (even if sentinel node biopsies are negative). They also might suggest the severity of the cancer, which would help determine whether treatments should be more or less aggressive. A number of proteins and other factors detected in blood tests are showing promise as markers for microscopic metastasis. Examples include antibodies to MART-1, Melan-A, tyrosinase, and microphthalmia transcription factor (Mitf). Combinations of some of these factors may improve detection rates.

Risk Factors for Determining Prognosis

To reach a prognosis, other factors in addition to staging must be considered such as gender, age, and location of the melanoma. All cases are unique, however, and the presence of any of these factors should not discourage people from seeking all possible treatment options.

• Age. Patients older than 50 generally have the worst prognosis, perhaps because they tend to wait to see the doctor and thus have the thickest lesions.
• Gender. Although women and men fare equally well in the first 2 years after diagnosis, women appear to do a bit better after that time, particularly younger women. Prepubescent girls have a poorer prognosis than boys do (although it is very rare in children). This suggests, but does not prove, that estrogen may have some protective properties. The difference in gender may simply be due to women giving more attention to their skin.
• Melanoma Characteristics. Thick melanomas, those that are ulcerated (in which skin layers over the tumor appear indistinct on pathologic examination), and those that have invaded blood vessels tend to have a worse prognosis.
• Original Site. Patients with melanomas that arise within preexisting moles may fare better than those with new lesions. Some studies indicate that melanomas furthest away from the trunk, particularly the feet, were associated with poorer survival, but this may be because such areas are less likely to be observed and so such melanomas tend to be diagnosed at a late stage.
• Metastasis. Survival rates are worse if the cancer has spread, particularly to the gastrointestinal tract, liver, or lung. In any case, the more sites that the cancer has spread to, the poorer the prognosis.
• Regression. In some people, melanomas spontaneously stop growing for a time and may actually shrink in size, which is a favorable sign.

Staging Melanomas If melanoma is diagnosed, health professionals have devised various methods for staging (assessing the severity of) the cancer. This report now uses the new staging system recommended by American Joint Committee on Cancer, which should improve the precision of predicting outcome and determining treatments. The stages use the following abbreviations: T = tumor. T is followed by a number to indicate thickness. N = node. N is followed by numbers to indicate the number of lymph nodes involved. M = metastasis. In addition a stage will include whether the melanoma is ulcerated or not, an indication of severity. Ulceration is determined if skin layers over the tumor appear indistinct under the microscope. In general, the thicker the lesion and the farther the cancer has spread, the higher the assigned stage. The higher the stage, the worse the long-term outlook. The earliest melanomas, which do not penetrate beneath the surface of the skin and are known as melanoma in situ, are highly curable and are called stage 0 or not given a stage. Others are staged as follows: Stage I. Cure rates are excellent, 80% to 100%, with surgical removal, since they are least likely to have spread Stage 1A. Tumor has not spread to the nodes. It is less than 1 mm and is not ulcerated. Stage IB. Tumor has not spread to the nodes. It is less than 1 mm, but is ulcerated, or the tumor is between 1.01 and 2 mm but is not ulcerated. Stage II . Melanomas can be cured, but the success rate (60% to 80% five-year survival) lags behind that of Stage I because a small number of cancer cells may have escaped from the original lesion and seeded distant sites. In addition to surgery, other forms of therapy may be recommended. Stage IIA. Tumor has not spread to the nodes. It is between 1.01 and 2 mm and is ulcerated, or it is 2.01 to 4 mm without ulceration. Stage IIB. Tumor has not spread to the nodes. It is between 2.01 and 4 mm and is ulcerated or greater than 4 mm without ulceration. Stage III. Patients have a 30% to 70% five-year survival. Stage IIIA. Tumor has spread to 1 node and it is up to 4 mm without ulceration. Sentinel biopsy has detected microscopic evidence of tumor cells in the node (micrometastasis). Stage IIIB. Tumor is up to 4 mm without ulceration and has spread to one node or there is evidence of micrometastasis in two nodes. Stage IIIC. Tumor is any thickness and ulceration may or may not be present. It has spread to 2 or 3 nodes. Additional "satellite" melanomas on the skin more than 2 cm (about an inch) from the original lesion may be present; these are sometimes called "metastases in transit."

• Review Date: 6/7/2006
• Reviewed By: Harvey Simon, M.D., Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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