Cancer: Melanoma

The information in this section has been gathered from existing peer-reviewed and other literature and has been reviewed by expert dermatologists on the CSPA Medical Advisory Board.

Melanoma is a cancer that begins in the pigment-producing cells (melanocytes) of the skin. It is considered the least common yet the most serious of the three main types of skin cancer, which also include basal cell and squamous cell cancers [link to skin-cancer: non-melanoma section].

Skin cancer results from cells that multiply out of control. As a result, tumours, lumps, or masses can sometimes form on normal skin, and can be either benign (non-cancerous) or malignant (cancerous). Some types of cancer are more likely than others to spread to other parts of the body and cause damage. This process is called metastasis. Melanoma is considered the most serious type of skin cancer as it may spread where it continues to grow and destroy tissue. If it is detected early, most melanomas are curable.

In its earliest stage, melanoma is confined to the outer layer of skin (the epidermis) and is known as in situ melanoma. If the melanoma goes undetected, it can grow deeper, penetrating the middle layer of skin (the dermis). At this stage, it is known as invasive melanoma.

There are four types of melanoma:

Superficial spreading melanoma (SSM) is usually diagnosed when people are in their 40s or 50s. It represents approximately 70 per cent of all melanomas. SSM can arise from a mole or on otherwise normal skin and most commonly occurs on the upper back in men and the upper back or legs in women. SSM usually looks like a deeply pigmented flat or slightly raised area.

Nodular melanoma (NM) accounts for 15 to 30 per cent of all cases. It most often appears in midlife, usually on the person’s trunk, head, or neck. The onset can be rapid, with NM often developing within several months. Unlike other types of melanoma, it is invasive from the onset and typically appears either as a uniform dark blue-black or bluish-red area, or as an area without any pigment.

Acral lentiginous melanoma (ALM) represents the most common form of melanoma in darker-complexioned people and Asians but occurs less frequently in people with light complexions (only 2 to 8 per cent). ALM occurs on the palms of the hands, soles of the feet, or beneath the nails. It can appear as a tan, brown or black flat lesion with changes in colour and irregular borders. It may often be under the nail as a brown to black discolouration. Most cases involve the big toe or thumb.

Lentigo maligna melanoma (LMM) has been likened to a stain on the skin. At the beginning, lentigo maligna (LM) is confined to the epidermis. If it extends into the dermis, it is termed LMM and is the least common type of melanoma. LM and LMM are almost always found on areas of the skin that have had long-term sun exposure, such as the nose, cheeks, head and neck. LMM most often occurs in older patients, beginning in the 60s. Frequently, the lesion is quite large (3–6 cm or larger). The colours in flat areas include tan, brown, black, blue-grey and white.

The risk of developing a melanoma is greater if a person has a family history of skin cancer, has a lot of moles, or has fair or freckled skin, blue eyes and light-coloured or reddish hair. However, anyone who has had excessive sun exposure, severe and frequent sunburns during childhood, or has lived in a sunny or high-altitude climate is at increased risk of developing skin cancer.

As with many other skin conditions, preventing melanoma is better than a cure. To reduce your risk, you should:

• Avoid prolonged sun exposure, especially between 11 a.m. and 4 p.m.
• Don’t use tanning beds or sun lamps.
• Apply sunscreen that has an SPF of 30 or higher and that protects against UVA and UVB rays, even in the winter. Reapply after swimming or sweating.
• Wear protective clothing, such as closed-toed shoes, hats that shade your face, long pants and long sleeves.
• Seek shade when you’re outside.