There are a number of factors which are associated with an increase in melanoma. These factors include:
Fair skin: Individuals who are fair or light skinned are more prone to skin cancers than dark skinned individuals. Having less of the pigment melanin in the skin makes one prone to melanoma. These same individuals also have a tendency to sunburn easily.
Other related factors which also increase the risk of melanoma include lightly colored eyes or those with freckles. Individuals from Northern Europe or from Australia are most prone to melanomas. However, this is not a rigid rule, as melanomas can also occur in dark skinned individuals and even blacks.
When melanoma occurs in dark skinned individuals, it is almost always diagnosed late as melanoma is never suspected. Whenever the diagnosis of melanoma is late, the prognosis is dependent on far deep the melanoma has penetrated into the skin.
Sunburns: Those individuals who sunburn easily and have a history of sunburns are also prone to developing skin cancers. The risk is greater if one has a childhood history of sun burns. For this reason, all individuals who have a history of sunburns should always wear protective clothing. Although adults can get sunburns, the greatest danger is sunburns that occur in childhood and the teenage years. Children and infants are most vulnerable to sun injury as they do not have the melanin pigment cells developed to protect them from UV light.
Excessive sun exposure. This is the highest risk for developing skin cancers and it is also the most preventable.
Sunny or high-altitude climates. Those individuals who live in the sunny parts of the world are more at risk than those living in the more temperate climates. Skin cancer is far more common in Florida than Michigan; likewise skin cancer is more common in Australia compared to Britain.
Moles: Having a single mole is not a risk factor for melanoma, but having a number of dysplastic moles makes one more susceptible to melanoma. The more moles one has, the higher the risk of melanoma.
Family history: Melanoma has a tendency to run in families. If anyone in the family has had a history of melanoma, the chances are greater that other members of the family may develop the cancer. There are certain familial syndromes whereby melanomas occur more frequently. These families are affected by a condition known as familial atypical mole-malignant melanoma (FAMMM) syndrome. The hallmarks of FAMMM include a history of melanoma in one or more close relatives and having more than 50 moles, some of which are atypical. People with this syndrome have an extremely high risk of developing melanoma.
Weakened immune system. Individuals who are immunosuppressed and have other cancers are more at risk for developing skin cancers.
Exposure to carcinogens. The American Cancer Society has identified several substances that may contribute to melanoma, including coal tar, the wood preservative creosote, arsenic compounds in pesticides and radium.
Rare genetic disorder. People with xeroderma pigmentosum, which causes an extreme sensitivity to sunlight, have a greatly increased risk of developing melanoma because they have little or no ability to repair damage to the skin from ultraviolet light.
Idiopathic: With many cases of melanoma, there is no identifiable risk factor for melanoma and the cancer occurs spontaneously. This is simply due to bad luck.