Skin cancer is the commonest cancer worldwide accounting for about 30% of all cancer diagnoses and affecting 10,000 people in Ireland every year. The lifetime risk of developing skin cancer is about 15% in males and 10% in females, yet remains one of the most preventable cancers.
The vast majority of skin cancers (90%) are caused by over exposure to UV radiation from sunlight or sunbeds leading to redness, burning or tanning but causing ultimately damage to skin cells. Unfortunately, in Ireland, it is predicted that the number of skin cancer cases will double by 2040 which reflects in part increasing sun holiday travel.
In spite of this, as the old adage goes prevention is better than cure and avoiding excessive sun exposure as well as checking for skin lesions is important. If spotted early, up to 90% of cases are curable and crucially detecting melanoma early can be life saving.
Risk factors for skin cancer include having pale skin that burns easily, previous sun burn in the past (especially with blisters and occurring in childhood), chronic or intense episodic sun exposure, use of sun beds, having multiple or unusual moles, previous skin cancer or a family history of melanoma.
In particular, those in occupations with outdoor exposure have greater risk and indeed about 25% of skin cancer deaths in Ireland are from the outdoor, construction and farming sectors. Those involved in outdoor activities like golf and sailing also have an increased risk. Skin cancers frequently occur in areas which are often unknowingly exposed such as on the nose and ears and can also be easily missed when they occur on the back.
Crucial to preventing skin cancer is minimising sunlight exposure particularly between the hours of 10am to 3pm between March and October when there is the greatest risk of burning. Sunscreen should be used when directly in the sun and needs to be applied generously when out (and every two hours if in contact with water).
It should have at the very least a protection factor of 15 and ideally 30 to protect against both UVA and UVB. However, sunscreen alone is not an alternative to covering up with suitable clothing, seeking shade, wearing sunglasses and protective hats. It is also important to remember that it’s possible to burn on a cool or cloudy day.
While there has been some controversy about avoidance of sun exposure and sunscreen use as contributing to vitamin D deficiency, in reality about only 15 minutes in the sun at any one time is needed for cutaneous vitamin D synthesis. In fact, exposing for longer will not boost your vitamin D level any further.
Skin cancer lesions are usually painless and may grow slowly over months to years. The most common (basal cell) rarely spreads to other parts of the body but left untreated can cause ulceration and in particular damage to eyes, nose and ear. It usually presents as a red patch or irritated skin area, a shiny bump or pink nodule or as a scar like lesion.
On other hand, squamous cell lesions (which tend to occur on the back of hands, balding scalp, forearms, shin and face) often appear as red or scaly but also as a flat sore causing pain and can grow relatively quickly over weeks to months. In particular, they can spread to other areas especially if they occur on the lips or ears.
Suspicious skin lesions are usually surgically removed or treated with freezing using liquid nitrogen, though topical creams may be used instead.
Melanomas are the most serious of skin cancers, can be life threatening and account for about 10% of all cases. It ranks as one of the most aggressive of all cancers and has been previously described as the tumour that used to give cancer a bad name. It results primarily from damage to the skin’s pigmented cells (melanocytes) and may arise from within moles but also on normal-looking skin.
Sun exposure in childhood and adolescence leading to early skin damage is a big risk factor. When diagnosed early it can be cured with simple surgery, though lesions that have spread deeper below the skin are often incurable.
Melanomas usually look like a freckle or mole that is changing or growing. Concerning features also include moles that are asymmetrical, have irregular borders, or more than one colour (blue, brown or black) and are greater than 6mm in size, cause itch, pain or bleed.
Most moles are acquired early in life and will usually not change in appearance so if you detect any variation it is important to get it checked out. It’s also important to check skin areas like your back where it is easy to miss lesions.
Sunbed use is a very high risk for melanoma as well as other skin cancers. They may emit radiation up to 15 times as strong as that from peak midday sun and their use before the age of 35 appears to increase the risk of malignant melanoma by 60%. Indeed, sunbed use in those aged under 18 is banned in Ireland and most health bodies recommend avoiding their use altogether.
So remember to keep your skin well protected and be vigilant for any new or changing skin lesions. If you have any doubts, go to your GP to get checked out.
Dr Kevin McCarroll is a Consultant Physician in Geriatric Medicine, St James’s Hospital, Dublin.