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SIGN decision support

Prevention , risk factors and genetic testing

Cutaneous melanoma (SIGN)
Healthcare Improvement Scotland

Prevention

Advice for primary prevention:

  • use clothing as the primary means of protecting against the sun
  • people of fair complexion should be especially careful about sun exposure
  • avoid using sun beds, tanning booths, and tanning lamps as an increased risk has been reported
  • use broad spectrum sunscreens with a minimum sun protection factor (SPF) of 30, and 4 or 5 UVA stars, in addition to sun avoidance and other sun-protective measures, providing this does not lead to increased time spent in the sun
  • avoid exposure to direct, intense sunlight, especially between 11am and 3pm (eg seek out shade)
  • provide children with appropriate sun protection for outdoor activities.

Risk factors

Individuals identified as being at higher risk should be advised about appropriate methods of sun protection, educated about the diagnostic features of cutaneous melanoma and encouraged to perform self examination of the skin.

Risk factor OR* Information
11–50 common moles >2 mm 1.7 to 1.9 The risk of melanoma rises with the number of common moles.
51–100 common moles >2 mm 3.2 to 3.7  
>100 common moles >2 mm 7.6 to 7.7  
Family history of melanoma 1.8 Melanoma in a first degree family member (parent, sibling or child of the patient).
Previous history of melanoma   Standardised incidence ratio range 4.5 to 25.6
The presence of 1–4 atypical moles 1.6 to 7.3 Atypical moles: ill-defined or irregular border; irregular pigmentation; diameter >5 mm; erythema (blanchable in lesion or at edge); accentuated skin markings.
Red or light-coloured hair 1.4 to 3.5  
Presence of actinic lentigines 1.9 to 3.5 Actinic lentigines: flat, brown skin lesions associated with acute and chronic sun exposure. No direct malignant potential.
Giant congenital melanocytic naevi ≥20 cm in diameter   Relative risk range 239 to 1,224 for extracutaneous as well as cutaneous melanoma.
Unusually high sun exposure 2.6  
Reported growth of a mole 2.3  
Skin that does not tan easily 1.98  
Light-coloured eyes 1.55 to 1.60  
Light-coloured skin 1.40 to 1.42  
Affluence   Relative risk approximately 3.0 for people residing in areas defined as Carstairs deprivation category 1 (least deprived) compared to Carstairs category 7 (most deprived).
Age   Melanoma is rare in absolute terms in childhood and adolescence. Risk begins to increase with age during adolescence, the elderly being at highest risk. The validity of some risk factors, such as hair colour and sun exposure, is lower in the elderly.

*OR = odds ratio. In some cases the range of ORs from more than a single study are given.

For example: a person with skin that does not tan easily has an approximately two-fold (1.98 times) risk of developing melanoma compared to someone with skin that tans (after allowing for other risk factors). This is modest in comparison, for example, to the approximately 10-fold or greater risk of developing lung cancer in someone who smokes cigarettes compared to a person who has never smoked.

All patients with melanoma and a history of immunosuppression should have a multidisciplinary team approach to care. Minimising the immunosuppressive therapy should be considered where possible.

Genetic testing

There may be benefit for patients to undergo genetic counselling for genetic testing as a higher compliance in self examination has been reported after genetic testing. People with mutations in CDKN2A, associated with melanoma and pancreatic cancer, may have a higher risk of smoking-related cancers and so should be advised to abstain from smoking tobacco.

Genetic testing for mutations in CDKN2A should be offered to an affected individual who has a first degree relative affected by melanoma or pancreatic cancer.