Understanding Melanoma

Melanoma is the least common skin cancer but the most important to catch early. It’s almost always curable when found early, but it can become deadly if allowed to spread. Important things to know:

  • Melanoma must be taken seriously. It is more likely than other skin cancers to spread.
  • Exposure to ultraviolet rays, from the sun or tanning beds, is a main cause of melanoma.
  • Oregon has a high rate of melanoma cases compared with other states.
  • Rates have been increasing for the past four decades.
  • Melanoma can strike anyone but is much more common in whites than in other races.
  • Melanoma is more common in older people but is also one of the most common cancers among young adults.

                                               Skin Anatomy

A diagram illustrating the anatomy of a melanoma.

What is melanoma?

Melanoma is a type of cancer that arises from pigmented cells called melanocytes. It most often occurs in melanocytes in the skin’s top layer. Less often, melanomas form in other parts of the body, such as the eyes and mouth.

Who gets melanoma?

More than 91,000 new skin melanomas are expected to be diagnosed in the U.S. in 2018, according to the American Cancer Society.

Causes and risk factors

Sun exposure: Damage from repeated exposure to ultraviolet rays — from the sun or sources such as tanning beds — is a factor in roughly half of melanomas. Ultraviolet rays damage the skin’s DNA, which can lead to cancer.

Family and medical history: About half of melanoma cases are linked to an inherited genetic trait. If a close relative — a parent, brother, sister or child — has had melanoma, you are at a slightly higher risk. Also, if you’ve had melanoma or basal or squamous cell skin cancer, you are at higher risk. OHSU offers expert genetic counseling and testing to learn about your risk and how to manage it.

Region: Oregon is among the top 10 states for melanoma cases. On average, more than 1,200 people a year were diagnosed with melanoma from 2010-14, according to the National Cancer Institute. That amounts to 27 cases per 100,000 residents, or sixth-highest in the U.S. Within Oregon, Deschutes County had the highest incidence, with nearly 40 cases per 100,000 residents.

Race/ethnicity: Melanoma is 20 times more common in whites than African-Americans, and five times more common in whites than Latinos. If you’re white, your lifetime risk of getting melanoma is about 2.5 percent. Whites with fair skin and with red or blond hair or blue or green eyes are at increased risk.

Age: About 70 percent of cases are diagnosed in people age 55 or older. At the same time, melanoma and breast cancer are the most common types of cancer among those ages 25 to 39.

Gender: Melanoma is more common in men, but that varies by age. For those younger than 50, women are at higher risk. For those older, men are.

Survival rates

A diagram to visualize the survival rates of people with thyroid cancer.

Nearly 92 percent of patients survive at least five years after diagnosis with melanoma. The rate is 98 percent for patients diagnosed before the cancer has spread from its original site. Those diagnosed after cancer has spread to lymph nodes or other parts tend to have shorter survival times.

It’s important to remember that these are averages. Your outlook will vary based on factors specific to you.

Melanoma symptoms

Most moles are normal and harmless. But if you notice a mole that seems different, talk to your doctor. It’s important to be familiar with your own skin so you recognize when something looks different.

You can also use the ABCDE guide:

An asymmetrical melanoma

  1. Asymmetry: One side is not like the other.

A melanoma with irregular edges

  1. Border: The edges are irregular or ragged.

A melanoma with color variations

  1. Color: It has color variations, such as shades of brown or black, sometimes with patches of pink, red or white.

An example of a melanoma, which is typically more than 6mm in diameter.

  1. Diameter: It’s more than 6 millimeters across (the size of a pencil eraser), though it can be smaller.

An example of a mole that has changed in some way over time.

  1. Evolving: The mole may change in size, color or shape.


Other symptoms to watch for:

  • A sore that doesn’t heal
  • Swelling or redness beyond the mole’s border
  • Itchiness, tenderness or pain at the mole
  • A mole that is scaly, that oozes or bleeds, or that includes a lump or bump


Superficial spreading melanoma: This type accounts for about 70 percent of cases. It's the most common type in young people. The first symptom is a flat or slightly raised discolored patch with irregular borders. The patch may be tan, brown, black, red, blue or white. It can be anywhere on the body but is most likely on the upper back, or on the torso in men and the legs in women. This melanoma grows on the top skin layer for quite a while before invading deeper tissue.

Lentigo maligna: This type also stays close to the skin surface for a while. Most often, it appears flat or slightly elevated. It's most often tan, brown or dark brown. This type, which occurs in about 10 to 15 percent of melanoma cases, is most often found in the elderly.

Acral lentiginous melanoma: This type occurs in 2 to 3 percent of melanoma cases. It usually appears as a black or brown discoloration under the fingernails or toenails or on the palms or on the soles of the feet. This type is most often found in dark-skinned people and is the most common melanoma in African-Americans and Asians.

Nodular melanoma: This type is often invasive by the time it is diagnosed. It often appears as a bump that’s usually black but sometimes brown, tan, red, white, blue or gray. This is found in 10 to 15 percent of melanoma cases and is the most aggressive type.


Staging helps guide treatment recommendations. Your care team will determine the stage based on:

  • How deeply the cancer penetrates your skin
  • Whether cancer has spread to your lymph nodes and/or other parts of your body

Stage I: The melanoma is less than 1 millimeter thick and is not found in the lymph nodes or other parts of the body.

  • Stage IA: The melanoma is less than 0.8 millimeter thick and has no ulceration (open sore).
  • Stage 1B: The cancer is less than 0.8 millimeter thick and ulcerated, or between 0.8 and 1 millimeter thick and ulcerated or not.
Stage II Melanoma
A diagram illustrating Stage II melanomas.

Stage II:  The cancer is thicker but not in the lymph nodes or other parts of the body. 

  • Stage IIA: The melanoma is 1.01 to 2 millimeters thick and is ulcerated. Or it’s between 2.01 and 4 millimeters thick and not ulcerated.
  • Stage IIB: The cancer is 2.01 to 4 millimeters think and is ulcerated, or is thicker than 4 millimeters and not ulcerated.
  • Stage IIC: The melanoma is greater than 4 millimeters thick and is ulcerated.

Stage III: The melanoma has spread to nearby skin areas and four or more lymph nodes but has not spread elsewhere in the body.

  • Stage IIIA: The cancer is 2 millimeters thick or smaller, and has spread to one lymph node.
  • Stage IIIB: The cancer is up to 4 millimeters thick and has spread to up to three lymph nodes. Or there is no evidence of the primary tumor, but melanoma is found in one lymph node or found in a nearby area of skin.
  • Stage IIIC: The cancer is up to 4 millimeters thick and has spread to four or more lymph nodes. Or it's greater than 4 millimeters thick and has spread to up to three lymph nodes. Or there is no evidence of the primary tumor, but melanoma has spread to four or more lymph nodes or to a nearby area of skin.
  • Stage IIID: The cancer is more than 4 millimeters thick and has spread to four or more lymph nodes or a nearby area of skin.

Stage IV: The melanoma has spread beyond the original area of skin and nearby lymph nodes to other organs in the body, such as the lungs, liver or brain.

Learn more

OHSU resources

Melanoma and skin cancer information