Melanoma

Melanoma is a skin cancer that originates in the pigment-producing melanin skin cells (melanocytes). It is the fastest increasing cancer in incidence in the U.S., and possibly in the world. Factors that influence a person’s risk of contracting melanoma include sun exposure, the number of moles on the skin, skin type, and heredity/genetics. Melanoma is nearly 100 percent curable with early surgical intervention, however once it spreads to other parts of the body, it is more difficult to treat and can be fatal. Melanoma usually occurs on the skin (cutaneous melanoma), but it also occurs in mucous membranes such as the inside of the mouth (mucosal melanoma), and in the eye (ocular melanoma). Approximately 77,000 new cases of metastatic melanoma are diagnosed in the United States each year, and approximately 9,500 people die from the disease.

Risk Factors

The most important risk factor for melanoma is exposure to ultraviolet radiation, which comes from the sun (as well as artificial light from tanning beds and tanning lamps). UV rays damage the DNA of skin cells through slow daily exposure, and sunburns also raise the risk of melanoma. UV exposure during childhood and young adulthood can contribute to the formation of cancers many years or decades later.

Other risk factors include:

  • Family history of melanoma
  • Caucasian ancestry
  • Fair skin, freckles, light hair
  • Unusual mole or spot
  • Presence of many moles
  • Age. Although melanoma is more likely to occur in older people, it is now one of the most common cancers among people under age 30.

Causes

Changes in DNA can cause cells to become cancerous. When UV radiation damages DNA in the skin, this damage sometimes causes cells to become cancerous. The DNA of certain genes is often damaged in melanoma cells. Some people’s cells repair damage better than others; those who are less able to repair such damage may be more likely to develop melanoma.

In some families, mutations of specific genes increase the risk of melanoma. Familial melanomas most often show changes in tumor suppression genes such as CDKN2A (also known as p16) and CDK4.

Symptoms

Unusual moles, markings, sores, lumps, or blemishes could be signs of melanoma and should be carefully checked by a physician.

The standard guideline regarding skin lesions is the ABCDE rule, as provided by the American Cancer Society:

  • A is for Asymmetry: One half of a mole or birthmark does not match the other.
  • B is for Border: The edges are irregular, ragged, notched, or blurred.
  • C is for Color: The color is not the same all over and may include shades of brown or black, or sometimes with patches of pink, red, white, or blue.
  • D is for Diameter: The spot is larger than 6 millimeters across (about ¼ inch – the size of a pencil eraser), although melanomas can sometimes be smaller than this.
  • E is for Evolving: The mole is changing in size, shape, or color.

Since some melanomas do not fit the rules described above, it is important to tell your doctor about any changes or new spots on the skin, or growths that look different from the rest of your moles.

Other warning signs are:

  • A sore that does not heal
  • Spread of pigment from the border of a spot to surrounding skin
  • Redness or a new swelling beyond the border
  • Change in sensation – itchiness, tenderness, or pain
  • Change in the surface of a mole – scaliness, oozing, bleeding, or the appearance of a bump or nodule

Diagnosing Melanoma

Diagnosis of a suspicious mole or blemish may require a number of tests in order to diagnose whether it is a melanoma, a non-melanoma skin cancer, or another type of skin condition.

A thorough medical history is taken, followed by careful physical examination. Your doctor will pay close attention to signs including:

  • Size, shape, color, texture of areas in question
  • Symptoms such as scaling or bleeding
  • Enlargement of lymph nodes, which could indicate spread of a melanoma

A dermatologist may perform a range of tests, depending on his or her findings.

Dermatoscopy (also known as dermoscopy, epiluminescence microscopy [ELM], or surface microscopy) uses light and a magnifying glass to better see spots on the skin.

Biopsies

If melanoma is suspected, biopsies may include the following:

  • Skin biopsy: removal of a small sample of the skin
  • Shave biopsy: removal of the top layer or layers of the skin with a small surgical blade
  • Punch biopsy: removal of deeper layers of the skin using a tool that resembles a tiny cookie cutter
  • Incisional biopsy: removal of a sliver or wedge of the full thickness of the skin. Incisional biopsies remove part of the tumor but not the whole tumor.
  • Excisional biopsy: removal of the entire tumor, which is preferred if the lesion is suspected to be melanoma.
Biopsy of melanomas that may have spread

Biopsies of the lymph nodes or other areas of the body may be needed to determine if melanoma has spread, or in the event that other types of cancer are present, because different cancers are treated differently.

Fine needle aspiration biopsy is used to evaluate large lymph nodes near a melanoma to determine whether it has spread to these nodes.

Surgical (excisional) lymph node biopsy is the removal of tan enlarged lymph node to see if melanoma has spread.

Samples taken during biopsies are sent to the pathology laboratory, where they are examined under microscopes and tested.

Imaging Tests

Imaging tests may be performed to determine whether melanoma has spread to other parts of the body, to determine how well treatment may be working, or to check for recurrences.

  • Chest x-ray may be used to check for spread to the lungs.
  • CT scans can provide detailed images of soft tissues including lymph nodes and internal organs throughout the body.
  • MRIs also give detailed images of the soft tissues of the body, and are particularly useful for the brain and spinal cord.
  • PET scans (positron emission technology), which shows the metabolic activity of cells in the body, is useful in identifying advanced stages of melanoma.

Stages of Melanoma

The stage of a cancer refers to how widespread it is, and includes the thickness of the cancer, whether it has spread to lymph nodes or other organs, and other factors.

The most common system used in determining the stage of a melanoma is the American Joint Commission on Cancer (AJCC) TNM system. The main categories of this system are:

T: tumor – how far the tumor has grown within the skin, and other factors. Assigned a number from 0-4.

N: spread to nearby lymph nodes, collections of immune cell thickness where tumors often first spread. Assigned a number from 0-3.

M: metastasis – whether the cancer has spread to other organs, which organs are affected, and whether the blood contains elevated levels of LDH, which may be associated with poor prognosis.

The TNM system is complicated and contains many sub-categories. See the American Cancer Society for a more detailed description of this system.

After the T, N, and M groups have been determined, an overall number is assigned from I to IV, with stage IV being the most advanced. People with stage I or II cancers have a better prognosis than those with stage III or IV.

Prevention

The best way to reduce the risk of melanoma is to limit exposure to UV radiation. Avoid all tanning beds and sunlamps, and take precautions when outdoors.

A popular slogan reminds us to Slip, Slop, Slap, and Wrap:

  • Slip on a shirt.
  • Slop on sunscreen.
  • Slap on a hat.
  • Wrap on sunglasses to protect the eyes and sensitive skin around them.

The Melanoma Center offers screening with full-body-scan MoleMap technology for high-risk patients, risk stratification (assessment of all factors known to contribute to an individual's risk of contracting melanoma), and support groups for melanoma patients and their families.

Treatment

For information about treatment of melanoma, see Tumor Immunotherapy.