Melanoma

About the disease

Melanoma is a deadly skin cancer that begins in the melanocytes, the cells producing a pigment called melanin that colours the skin, hair, eyes and moles.

It is the fastest growing cancer in the world and has been labeled an epidemic by some experts. Melanoma is the most common cancer among young adults 20-30 years old, although it can be diagnosed at any age. While most other skin cancers don’t travel, melanoma can spread throughout the body. Melanoma makes up the smallest portion of all skins cancers, about 5 per cent, but accounts for nearly three quarters of all skin cancer deaths. It is, however, considered curable if caught early.

Superficial spreading melanoma is the most common of four basic categories of melanoma accounting for 70 per cent of diagnoses. It can be a variety of colours, and travel along the top layer of the skin before penetrating more deeply. Superficial spreading melanoma can occur anywhere, but is seen most commonly on the legs or upper back of women and on the trunk or upper back of men. It is the most frequent type of melanoma found among young people.

Lentigo maligna also remains close to the skin surface and usually appears as a slightly elevated brown or mottled discoloration. It is found mostly commonly in the elderly, and usually appears on the face, ears, arms and upper trunk.

Acral lentiginous melanoma usually appears under the nails, soles of the feet or palms of the hands. It is the least common form and affects predominantly those of Asian or African background.

Nodular melanoma is invasive from the start and is usually recognized when it becomes a bump. It is most often black in colour, but can also appear as other colours. This is the most aggressive form or melanoma, occurring predominantly in the elderly and usually appearing on the scalp, trunk, legs and arms.

About 350 Albertans are diagnosed with melanoma every year.

Risk Factors

Risk factors are determined by analyzing the numbers of patients with cancer in a larger population and trying to find differences in the characteristics or behaviors between those individuals who develop cancer and those who do not. The Alberta Cancer Board’s Tomorrow Project, for instance, is tracking more than 50,000 Albertans over a fifty-year period to learn more about who develops cancer and why.

Exposure to the sun is the most widely known factor that can affect the chance of getting melanoma. Both UVA and UVB rays are dangerous, but blistering sunburns in childhood also increase the risk as does cumulative exposure. The best way to protect the skin is to wear clothing with a tight weave and a broad-rimmed hat in combination with a sunscreen with an SPF factor of at least 15. Some medications also increase the skin’s sensitivity to sunlight.

Other factors that may increase the risk of developing melanoma include:

• Use of tanning booths
• Moles – people with more than 50 or any larger than a pencil eraser
• Skin type – fair skinned people with freckles; white or blonde or red hair; Green or blue eyes
• Medical history – being diagnosed previously with melanoma, basal cell carcinoma and squamous cell carcinoma (other forms of skin cancer)
• Weakened immune system – through chemotherapy or diseases such as HIV/AIDS or lymphoma
• Occupation: outdoor work at a golf course, swimming pool, construction site; an outdoor job for three or more years as a teenager
• Age – half of cases are diagnosed among those in their 50s
• Gender – men face a greater lifetime risk
• Environment – exposure to coal tar, creosote (a wood preservative) and arsenic compounds in pesticides and radium

Factors that may decrease the risk of developing melanoma include:

• Use of sun screen
• Avoidance of tanning beds
• Covering up in the sun
• Darker skin tone
• Monitoring moles through monthly self-exams
• Routine exams of moles by a family doctor or dermatologist
• Use of wraparound sunglasses that provide 100 per cent UV protection

Genetic Link

Melanoma in the immediate family (mother, father, siblings or children) increases the risk by 50 per cent over people who do not have a family history of the disease. The risk is not as great but is still increased if the disease has been diagnosed in the extended family (grandparents, aunts, uncles, nieces, or nephews).

About ten per cent of those diagnosed with melanoma have a family member with the disease.

Detection and Diagnosis

Moles, brown spots and growths on the skins are usually harmless but are the warning signs of melanoma. The medical community uses the ABCDEs to judge if further tests are required:

Asymmetry – the halves of the mole do not match

Border – the edges of early melanoma are jagged and uneven

Color - a variety of colors with various shades or brown, black, red, white or blue

Diameter – usually larger than a pencil eraser (1/4 inch or 6 millimeters)

Elevation or Evolving – the mole is raised above the skin and has a rough surface, or is changing shape, size or colour. It begins itching or bleeding.

A biopsy of the skin is needed to confirm the presence of cancer. It is done under local anesthetic. The doctor may also examine the lymph nodes to see if they are enlarged, a sign the melanoma may have spread.

In cases where melanoma has spread to other parts of the body, a CT or PET scan, MRI or chest X-ray may be needed.

Treatment

Treatment options for melanoma include surgery, chemotherapy and radiation therapy, sometimes in combination depending on the progression of the disease. The treatment depends on how far the melanoma has penetrated through the layers of the skin and how much it has spread.

Surgery is most commonly used to treat and usually cure the early stages of melanoma. These “resections” don’t usually require hospitalization and can often be done in a doctor’s office or as an outpatient procedure. The melanoma is removed, along with the “margins”, or the healthy skin bordering the tumour. Today’s techniques require the removal of less skin than in the past.

If the melanoma cells have spread, the surgeon would check the nearby lymph nodes, which may have to be removed as well.

When melanoma occurs on part of a finger or toe, it may be necessary to amputate.

Chemotherapy has been used for the treatment of melanoma, but so far the effectiveness of the available drugs has been limited. It may be more effective when used in combination with immunotherapy.

Immunotherapy has met with some success in the treatment of melanoma. This treatment is designed to boost the body’s immune system to allow it to fight off the cancer cells. It can also decrease the impact of side-effects from other types of treatment.

Radiation therapy, concentrated beams of high-energy X-rays, is not used for initial treatment of melanoma, but instead to treat the disease if it has reoccurred or spread. It can also be used to provide relief of symptoms if the melanoma has spread to the bones or brain.

Factors Affecting Prognosis

As with many cancers, early diagnosis is key. Superficial melanoma has a 100 per cent survival rate five years after diagnosis. In the advanced stages the five year rate falls to less than 10 per cent.

 Sun Safety information and handouts from the Alberta Cancer Board (on this website)
 National Comprehensive Cancer Network (U.S.) guide to treatment decisions with links to other sites 
 The Canadian Dermatology Association  
  Canadian Cancer Society