Skin cancer is the most common form of cancer in humans, but what exactly is it, how can we spot the signs, and how do we prevent it? DB Medical Centre’s Dr Yau Wing Him explains.
What causes skin cancer?
There are three different types of skin cancer: Basal Cell Carcinoma (BCC), Squamous Cell Carcinoma (SCC) and Malignant Melanoma. For BCC and SCC, risk factors are UV-radiation exposure, pale skin and ageing. With Malignant Melanoma the risk factors are UV exposure, sunburn, a fair complexion, increased number of moles, old age and family history. A variant of Malignant Melanoma occurs on the palms and soles, so not all are related to UV exposure.
Tell us more about BCC and SCC
BCC is the most common form of skin cancer, five times more common than SCC. Classically, BCC sees slow-growing pearly nodules on the face of an elderly person. These rarely spread elsewhere but they erode into surrounding tissue. SCC is the second most common skin cancer after BCC. Usually an ulcerated or crusted lesion is found on a bald scalp, or on the back of the hand or ear. It grows over a few months. The spread of SCC to other organs is a definite risk but rare. Smokers can develop SCC on the lower lip. Both BCC and SCC lesions are treated by surgical excision, with a cure rate of over 90%. Small superficial BCC and SCC may be treated with curettage and liquid nitrogen, immuno-stimulant or cytotoxic creams.
Is Malignant Melanoma treatable?
Malignant Melanoma is the most dangerous form of skin cancer. The five-year survival rate is improving (now upwards of 80%) but since a cure for this form of cancer is still being sought, we need to concentrate on prevention and early detection. Watch for the development of a new pigmented or unusual-looking growth on your skin, or changes to the shape or colour of existing moles. If diagnosed, surgical-wide excision of the whole suspected melanoma is required and sometimes removal of local lymph nodes. Surgery may be followed by chemotherapy or radiotherapy.
What is the connection between moles and melanoma?
As with SCC and BCC, most Malignant Melanoma develop as a lump on normal skin but 30 to 50% develop in a pre-existing mole. So a mole which is changing could indicate a melanoma. Look for ABCDE changes in a mole: Asymmetry; Border irregularity; Colour irregularity; Diameter over 6 millimetres; Evolving over time. Changes in size, shape and colour are more significant signs than itching, pain, or bleeding in any mole.
Can Actinic Keratoses become cancerous?
Actinic Keratoses are small, scaly red patches or yellow-white scaly crusts on sun-exposed skin. There is a very small risk they may turn into skin cancer (1:1,000 per year per lesion) but they may naturally regress. They are frequently multiple, and extremely common with increasing age. In some countries, over half the population over 40 has one or more lesions. If an Actinic Keratosis quickly increases in size, ulcerates, bleeds, or becomes painful, it may be transforming to SCC. They are easily and effectively treated with liquid nitrogen. If there are many lesions, immuno-stimulant or cytotoxic creams may be used.
How do we lower the risk of developing skin cancer?
People with fair complexions (especially those whose skin burns easily and never tans), anyone living under high sun exposure, outdoor workers, and those with a family history of Malignant Melanoma are most at risk. Six- to 12- monthly skin examinations are advisable. Public education is essential, for instance childhood sun exposure is strongly associated with skin cancer. Wearing protective clothing and hats, and using broad-spectrum sunscreens that protect against both UVA and UVB rays is important. Stay out of the sun!
You can contact Dr Yau Wing Him at the Discovery Bay Medical Centre on 2987 5633.