Skin cancers

There are over a thousand entities in dermatology; it is difficult to understand all in just a few pages. We are going to describe a few common skin problems. This is purely educational; if you have a skin disease, please consult your dermatologist.

The most common skin cancers are basal cell carcinoma(BCC), squamous cell carcinoma(SCC) and melanoma. They arise from basal cell layer, squsmous cells and melanocyes respectively. Fortunately, skin cancers are less common in orientals compared to Caucasians.

Basal cell carcinoma is the commonest cancer in the United States, and there are about 1 million new cases each year. About 10,000 die from BCC each year. Cumulative exposure to the harmful ultraviolet rays from the sun is the main reason for its development. Often, BCC arises 20-50 years after strong exposure under the sun. 80% of BCC are found in the head and neck. BCC tends to grow very slowly, and metastasizing is rare, so the fatality rate is not high. Despite this, BCC can erode into neighbouring tissue and if discovered late, potential multilating surgery may be required. Early found lesions can be treated with topical medication, cryosurgery, electrocautery and surgery.

Squamous cell carcinoma comprises 20% of all skin cancers. The risk factors of developing SCC are sun exposure, fair complexion, immunosuppressants, immunodeficient states, alcohol/smoking, poor nutritional status, contact with chemicals/heavy metal, chronic skin irritation and radiation. About 70% of SCC arise from the head and neck. Squamous cell carcinoma gradually enlarges over time and may have the appearance of an ulcer which fails to heal. The skin may thicken with a flaky appearance. Actinic keratoses and keratoacanthoma may arise before the development of SCC.

SCC may spread via the lymphatic system. Treatment includes topical medication, cryosurgery, Photodynamic therapy, surgery, chemotherapy and radiotherapy.

Although melanoma only comprises 4% of all skin cancers, it brings the highest mortality. Only periodic complete skin examination can effectively prevent morbidity and mortality. The risks include cumulative sun exposure, skin mutation, fair complexion, family history, multiple or dysplastic naevi, and old age.

In USA the lifetime risk of developing invasive melanoma is 1 in 57, being the sixth commonest cancer. In Australia, it is the fourth commonest cancer.

The symptoms and signs can be summarized as Assymetry, Border, Colour, Diameter >6mm and Evolutional changes.

The management will require skin biopsy to ascertain the level of invasion, and depending upon the result, treatment is surgical removal together with interferon treatment, chemotherapy and radiotherapy.