Skin cancer is the most common cancer in NZ and about 90% of cases seem to be related to sun exposure. New Zealand and Australia lead the world in high rates of melanoma. There are many different types of skin cancer but broadly speaking they can be divided into Melanoma (arising from the melanocytes or pigment cells of the skin) and non-melanoma cancers (arising from the epidermal skin cells).
The non-melanoma cancers are much more common with approximately 65,000 to 70,000 cases treated in New Zealand annually (2008 figures).
Basal Cell Carcinoma (BCC) is the most common skin cancer and provided it is treated early enough treatment cures the cancer. BCC does not spread to distant sites in the body but can cause problems when it arises close to important structures such as eyes, ears and nose. Tumours excised from such regions often need more complex plastic-surgical techniques to aesthetically reconstruct the skin defect that is created and avoid distortion. Generally surgical excision offers the highest rate of cure but superficial BCCs can be treated with a variety of other non-surgical techniques such as chemical treatment. Generally pale-skinned people with long cumulative sun exposure are at greatest risk for developing BCC.
Squamous Cell Carcinoma (SCC) occurs at about a quarter the rate of BCC and is potentially more serious. A small proportion will travel within the body and can appear at distant sites such as lymph nodes in groin, armpit or neck. Most SCCs when treated early do not spread. Again, SCCs can be problematic when near to important structures such as the eye or nose and may require specialised reconstructive surgery once the tumour has been removed. In most cases surgical removal offers the highest rate of cure but there other treatments such as chemical and radiation therapy also have a role. Chemical treatment is again particularly suitable for superficial SCCs. As with BCC, cumulative sun exposure is responsible for the majority of cases of SCC. Squamous Cell Carcinoma can be a particular problem for people who are immuno-suppressed such as those who are taking drugs to prevent rejection after kidney and heart transplants.
Although many cases of non-melanoma skin cancer arise in a given year there is a very low mortality rate.
New Zealand (with Australia) leads the world with high rates of Melanoma. There are about 2000 to 2500 cases annually (2,256 in 2008) and this makes it the fourth commonest cancer in the NZ Cancer Registry. As distinct from the non-melanoma skin cancers there is a relatively high mortality rate with over 250 deaths a year attributable to melanoma (versus 100 per year for non-melanoma). Because it can affect younger people melanoma is the leading cause of cancer deaths in New Zealand in the 25y to 44y age range. Melanoma is the most dangerous of all the skin cancers because it has the propensity to spread through the body via the lymphatic system or blood-stream.
Surgery offers the best hope of cure for melanoma but radiation therapy or chemotherapy can be used if surgery is not possible, or in conjunction with surgery. Treatment of melanoma depends on how advanced the disease is and the best chance of successful treatment is provided when the melanoma is picked up very early. Surgery for melanoma may be as simple as a 20-minute procedure under a local anaesthetic or may be a major operation lasting several hours depending on the severity of the disease.
Melanoma has a complex relationship with sun exposure and intermittent (for example; weekend) exposure may be more harmful than steady exposure. Pale skinned people with numerous moles are at higher risk.
The best way to reduce the effects of skin cancer is to prevent it altogether. Prevention of sunburn and excessive sun exposure can considerably reduce the risk of skin cancer. The NZ Cancer Society website (www.cancernz.org.nz) offers a range of advice on how to be SunSmart. Failing prevention, early detection offers the next best chance of successful treatment. The Cancer Society website also has information on what features of skin blemishes are most concerning.
It is important to seek professional advice on any skin lesion that is concerning you.