How does melanoma start?

Malignant melanoma is the most dangerous type of skin cancer and it begins from a skin cell called a melanocyte. Melanocytes exist normally in the skin and produce a pigment called melanin which helps to protect the skin from ultraviolet radiation. When there is an abnormal, uncontrolled (cancerous) growth of these melanocytes, melanoma results.

Who is at risk for melanoma?

Melanoma is most common in caucasians, but anyone can get melanoma. Australia and New Zealand have the highest rates of melanoma in the world. New Zealand women have the highest risk in the world, of getting melanoma – 40 per 100,000 every year. The risk for New Zealand men is 37 per 100,000 every year. Melanoma can occur in adults of any age but it is very rare in children. Melanoma is the most common cancer in people aged 20-39 years. The risk of getting melanoma increases as you get older. Approximately 1600 people in New Zealand are diagnosed with melanoma every year. About one in seventeen white-skinned New Zealanders are expected to develop melanoma in their lifetime.

Factors which increase the risk of melanoma

Intense intermittent sun exposure, particularly during childhood (50% increased risk)
Blistering sunburn, especially when young (double the average risk)
Previous melanoma (substantially increased risk for developing a second melanoma), or other skin cancers
Family history of melanoma (if a parent has had melanoma, the risk of getting melanoma is increased approximately 2.5 times, if a sibling had melanoma, the risk is increased approximately 3 times, and if a parent and a sibling have had melanoma the risk is increased approximately 9 times).
Fair skin (at least double the average risk)
Large numbers of moles (patients with more than 100 moles have approximately seven times the risk compared to patients with few moles)
Abnormal moles (larger than 5mm diameter with variable pigmentation and an irregular outline – markedly increased risk)