Melanoma

 

Information developed from NHMRC, Clinical practice guidelines for the management of cutaneous melanoma. http://www.nhmrc.gov.au/publications/synopses/cp68syn.htm

 

  1. In Australia, melanoma affects about 1 in 26 men and 1 in 34 women in their lifetime.
  2. The chance of developing melanoma increases with age, but affects people of all age groups.
  3. Melanoma is one of the most common forms of cancer in young adults.
  4. Risk factors for melanoma include:
  5. A personal history of:
  6. Melanoma occurring at an early age (median age of onset for familial melanoma is 33 years)
  7. Multiple primary melanomas
  8. Large number of naevi (more than 10 on the arms and 200 on the body)
  9. The presence of multiple atypical (dysplastic) naevi
  10. A family history of:
  11. Multiple cases of melanoma on the same side of the family
  12. Melanoma occurring at an early age
  13. Ocular melanoma
  14. Pancreatic carcinoma in more than one family member
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Genetics

  1. An inherited mutation in certain genes is thought to be involved in up to 5% of cases of melanoma.
  2. Two genes have so far been identified where it is believed that inherited mutations are associated with
    a predisposition to melanoma:
  3. CDKN2A codes for proteins that have a central role in controlling the process of cell growth and division. Gene mutations in the CDKN2A gene have been found in approximately 20 to 50% of families in different populations with three or more affected 1° relatives
  4. CDK4, mutations in which have been found in fewer families with multiple cases of melanoma
  5. Gene mutations in the CDKN2A and CDK4 genes follow an autosomal dominant pattern of inheritance, meaning that, if a person has a mutated copy of one of these genes, each of their children has a 50% chance of inheriting this gene mutation.
  6. Inheriting a gene mutation in one of these genes means an individual inherits a predisposition or
    susceptibility     to melanoma, and the risk of developing melanoma is higher than the population risk.
  7. The indicators that melanoma in a family could be due to an inherited mutation include:
  8. Three or more 1° or 2° relatives with melanoma
  9. Several primary melanomas in one person
  10. Young age of onset of the first melanoma (less than 40 years)
  11. The presence of atypical or unusual moles early in life
  12. These families would be candidates for participating in research programs where genetic testing for mutations in candidate genes may be performed.
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Management

  1. All individuals at potentially high risk of melanoma should be offered referral directly to a familial cancer
    service or through Genetics Services (see list of familial cancer services).
  2. Surveillance should be arranged in association with the familial cancer service, and discussions will include:
  3. Education about sun protection and early detection
  4. Intensive surveillance, commencing from age 10 years, including:
  5. Three-monthly self-examinations
  6. Whole-body photography, which may be used as a baseline
  7. Skin surface microscopy as a baseline
  8. Skin and scalp examination by a dermatologist, 6- or 12-monthly
  9. A low threshold for the excision biopsy of any suspicious lesions
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