Expert Opinion - Skin cancer and the role of sun protection

A GP and a nurse specialist assess current prevention measures. By Dr Elizabeth Ogden and Gill Godsell

A GP's VIEW
By Dr Elizabeth Ogden
The incidence of skin cancers in the UK is increasing and it is now predicted that in this country, one in three white-skinned people will develop a skin cancer at some time in their life.

Statistics on non-melanoma skin cancer are known to be understated, owing to incomplete reporting, but conservatively, figures are believed to be in excess of 100,000 cases annually for basal cell carcinoma (BCC).

Rates of melanoma have quadrupled since the 1970s and have shown a faster increase in incidence than any other major cancer. Melanoma affects a disproportionately large number of younger people and has now become the most common cancer in young adults (aged 15-34). In 2005, there were more than 8,000 reported new cases of melanoma and 1,600 deaths.

In Australia, skin cancer is more common than anywhere else in the world and the number of melanoma cases is higher than it is in the UK (9,524 in 2003) but mortality is lower (1,146 in 2003). This is believed to be due to greater public awareness and the availability of screening centres in Australia.

Early detection of skin cancers
The prognosis for melanoma depends on the depth of invasion, the Breslow depth, which is a histological diagnosis. The less the cancerous melanocytes have invaded the layers of the skin, the greater the chances of long-term survival.

A patient with a melanoma up to 1mm thick has a 97 per cent chance of surviving 10 years, but this drops to below 60 per cent if the melanoma is more than 4mm thick. If the melanoma has spread to lymph nodes, especially distant ones, by the time of diagnosis, the prognosis is very poor.

Melanomas on the scalp and neck are particularly prone to spread rapidly and although only 6 per cent present on these sites, they account for 10 per cent of deaths. Furthermore, one-third of melanomas present under the age of 50, making it one of the cancers with the highest number of years of life lost, indicating premature mortality. On average, about 20 years of life are lost for each melanoma death.

Melanoma is twice as common in young women as in young men, but more men die from their melanoma. This is because males are presenting later, with deeper melanomas. There is no successful additional treatment for melanoma after excision, although trials are continuing, so the most important action is early detection.

This requires the public to be knowledgeable and vigilant about skin changes suggestive of cancer and health professionals to be better trained in the diagnosis of skin lesions. On average, a GP may see a melanoma only once every four to five years, making it difficult to become proficient at diagnosis.

Melanomas can vary in appearance and the classic feature of dark colour can be absent in the most susceptible people - those with red hair and fair skin - whose melanoma can look pink and so is easy to misdiagnose. A dermoscope can help in lesion recognition because it reveals the pigment network, which helps to differentiate between moles and non-melanocytic lesions, as well as moles with irregular pigmentation.

Staging is important, so pigmented lesions should not be punch biopsied, curetted or shaved, unless there is no doubt about their benign nature. Under NICE guidelines, any changing pigmented lesion should be urgently referred.

Risk factors for skin cancer
Sun exposure is the main cause of melanoma and non-melanoma skin cancers. It particularly affects people with fair skin that freckles and burns easily. Red-haired and blonde people with blue eyes are especially at risk.

Freckles are a response to ultraviolet (UV) exposure and the first sign that the body has been overexposed. They are a marker of UV-induced damage and are an independent risk factor for the development of melanoma.1

The average person in the UK today has more sun exposure than previous generations, because of the increase in foreign holidays. The use of sunbeds, especially by young people, increases the risk of skin cancer, particularly melanoma.2 Unusually for cancers, melanoma has a positive correlation to affluence - wealthier people take more holidays.

A family history of skin cancer increases the risk for other family members and people with a large number of moles, especially if they are irregularly shaped, have a higher risk of melanoma.3 Solar lentigines (liver spots) have been shown to be an independent risk factor for the development of melanoma.

Chronic sun exposure is a risk factor in non-melanoma skin cancer. Rates of non-melanoma cancer in Australia are almost 400,000 a year in a population of 20 million.

Radiotherapy and immunosuppression also increase rates of non-melanoma skin cancer. Transplant patients are particularly susceptible to squamous cell cancer (SCC); their risk is at least 65 times higher. A patient who has had a non-melanoma skin cancer has a higher risk of developing a second one; 20 per cent of BCC patients develop another within five years.

Sunburn is a risk factor for melanoma, especially if it occurs in early life, and a history of sunburn is believed to double the risk of melanoma.4 Statistics in Australia show that children who migrate there before the age of 10 have a risk of melanoma similar to those born there, while those who migrate after the age of 15 have a much lower risk (one-third).5

Prescribing sunscreens
Prescription sunscreens are only available to four groups of patients - those with genetic diseases, such as Gorlin's syndrome and xeroderma pigmentosa, which make the skin excessively vulnerable to sun damage; those with photodermatoses, such as polymorphic light eruption, lupus or porphyria; after radiotherapy treatment and those with chronic or recurrent herpes simplex labialis.

- Dr Elizabeth Ogden, a non-principal GP in Hertfordshire, is an associate specialist in the department of dermatology, Lister Hospital, Stevenage, and does dermatology outreach clinics for West Hertfordshire Hospitals Trust Dermatology Clinical Assessment and Treatment Service

References
1. Rhodes AR, Albert LS, Barnhill RL, Weinstock MA. Sun-induced freckles in children and young adults: a correlation of clinical and histopathologic features. Cancer 1991; 67: 1990.
2. Gallagher RP, Spinelli JJ, Lee TK. Tanning beds, sunlamps, and risk of cutaneous malignant melanoma. Cancer Epidemiol Biomarkers Prev 2005; 14(3): 562-6.
3. Greene MH, Clark WH Jr, Tucker MA et al. High risk of malignant melanoma in melanoma-prone families with dysplastic nevi. Ann Intern Med 1985 102(4): 458-65.
4. Cho E, Rosner BA, Feskanich D, Colditz GA. Risk factors and individual probabilities of melanoma for whites. J Clin Oncol 2005 23(12): 2669-75.
5. Holman CD, Armstrong BK. Cutaneous malignant melanoma and indicators of total accumulated exposure to the sun: an analysis separating histogenetic types. J Natl Cancer Inst 1984 73(1): 75-82.

A NURSE'S VIEW
By Gill Godsell

As the most common cancer in the UK, with more than 100,000 new cases each year, skin cancer represents a significant health problem in the white adult population. Studies show that sun exposure and sunburn history play a considerable part in the development of skin cancer, so a key message must be to protect the skin against the harmful effects of the sun.1

Sunbathing has changed in the past 20 years, with a threefold increase in foreign holidays and a massive increase in the use of sunbeds. It is the responsibility of all healthcare professionals to educate patients on the importance of sun protection.

Sun protection messages
The key recommendations for sun protection include wearing long-sleeved clothing, sunglasses and a broad-brimmed hat, seeking shade, avoiding the sun when it is at its strongest (between 11am and 3pm) and using a sunscreen.

Babies under six months old should be kept in the shade at all times and pale-skinned infants and children under 12 years should be protected with a high factor sunscreen, such as SPF50. Children under 12 with brown or black skin should be protected with at least factor 30 sunscreen and those aged 12 and over should use at least SPF25.

All adults aged 18 or more should apply sunscreens rated at least SPF20 and those with a history of skin cancer should use SPF50. Sunscreen should protect against the effects of UVA and UVB and needs to be applied appropriately. Protection will be less than that stated if it is incorrectly applied.2 It should be put on up to 30 minutes before going into the sun, to allow it to dry and ensure it is not rubbed off by clothing, and reapplied every two to three hours. The British Association of Dermatologists recommends sunscreen to be applied as thickly as feasible and the bare minimum should be at least six full teaspoons of lotion to cover the body of an average adult.3

Studies have found that most people apply less than half of the amount required to provide the level of protection indicated on the packaging (so SPF50 becomes SPF25). Studies also show that sites such as the back and sides of the neck, temple and ears are commonly missed.3

Barriers to following the correct guidelines
A survey examining people's beliefs about reducing the risk of skin cancer showed that those who choose not to use sunscreen do so for various reasons, including the belief that their skin does not burn, they already have a 'protective' tan, sunscreens are expensive and greasy, or merely that they forget to apply them. In fact, sunscreens have improved and high factor sunscreens are cosmetically acceptable and easy to apply.3

A more recent reason quoted for not using sunscreen is that they prevent the skin from absorbing vitamin D, which has a key role in maintaining bone health. However, it has been stated that a 10-15 minute exposure of the hands and face two to three times weekly is adequate and the skin will reach its optimum level of vitamin D long before it has a chance to tan.4

Early detection
Lives can be saved by detecting and removing skin cancer early, so health promotion messages should highlight the signs of skin cancer and encourage the public to monitor their skin.

The ABCDE criteria (Asymmetry, Border irregularity, Colour variation, Diameter >6mm and Evolution) can be used to remind healthcare professionals and patients of the changes to look for and if anything suspicious is noted, advice should be sought from the GP.

If the GP is concerned, a referral can be made to the two-week wait skin cancer clinic in secondary care. A recent study showed that patients' ability to recognise irregularities significantly improved after training on how to use the ABCDE criteria.5

Information should also be provided about the signs of non-malignant skin cancer, which accounts for more than 80 per cent of all skin cancers and although less dangerous than melanoma, can be very disfiguring. Cancer Research UK has a range of leaflets and posters.

The prevalence of skin cancer is escalating at an alarming rate and we need to promote greater awareness, to ensure that people with suspicious lesions present to their GPs earlier. Primary health education is aimed at preventing the disease (sun protection) and secondary prevention is aimed at early detection (education and screening). As skin cancer develops decades after sun exposure, we need to approach prevention on both fronts, in an effort to reduce the incidence and mortality.

- Gill Godsell is skin care nurse specialist at the dermatology department, Nottingham University Hospital Trust

References
1. Gandini S, Sera F, Cattaruzza M et al. Meta-analysis of risk factors for cutaneous melanoma, II: sun exposure. Eur J Cancer 2005; 41(1): 45-60.
2. Diffey B. Sunscreens - considering perception versus reality. Dermatology in Practice 2005; 13(1): 14-16.
3. British Association of Dermatologists. Sunscreen and sun safety fact sheet. BAD, London, 2007.
4. Holick M. Sunlight and vitamin D for bone health and prevention of autoimmune disease, cancers and cardiovascular disease Am J Clin Nutr 2004; 80: 1678-88.
5. Robinson J, Turrisi R. Skills training for patients in use of the ABCDE criteria. Arch Dermatol 2006; 142: 447-52.


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