There are two main categories of skin cancer: melanoma and non-melanoma. Melanoma, also known as malignant melanoma, is the fifth most common cancer in the UK. It originates from melanocytes, the skin cells that produce melanin, the natural pigment that gives the skin its colour. The two main non-melanoma skin cancers (NMSC), also known as keratinocyte cancers, are basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). They differ from melanoma in developing from skin cells or keratinocytes in the epidermis, which is the outer layer nearest the surface of the skin.
What causes skin cancer?
The main preventable cause of skin cancer is damage to skin cells from exposure to ultraviolet (UV) radiation from the sun or sunbeds, especially during the first 20 years of life. People who have received a kidney or other solid-organ transplant are at higher risk of skin cancer, because the medications used to prevent rejection impair the immune system’s ability to repair or destroy cells damaged by UV radiation. The risk increases with time, so that in one UK study one third (32%) of people with a kidney transplant for more than 10 years had been diagnosed with NMSC.
According to Dr Eleanor Mallon: “The risk of developing skin cancer is said to be higher within the first five years of a kidney transplant. The type of immunosuppressant therapy is important. The risk is higher with azathioprine than with newer immunosuppressive drugs.” Eleanor is Consultant Dermatologist at Imperial College Healthcare and has a special interest in skin cancer.
Skin cancer risk is greatest in people with type 1 skin—i.e. with fair skin that freckles and always burns and never tans, and often with blond or red hair and blue or green eyes—than in people with type 5 or 6 skin that always tan and who are generally of Asian or African heritage. However, it is still possible for people with darker skin to develop skin cancer, especially after an organ transplant.
“The number of moles or melanocytic naevi increases the risk of melanoma, especially if the moles are different shapes, sizes and colours (called atypical mole syndrome). These people need particularly close monitoring, together with ‘mole mapping’ where each mole is photographed and held in a database that clinicians can consult should there be any history of change in an individual mole,” adds Eleanor.
Factors increasing the risk of skin cancer
- Skin that always or usually burns easily in the sun and never or rarely tans
- Past episodes of severe sunburn, often with blisters, particularly in childhood
- History of sun exposure; e.g. previously living in a country close to the equator, outdoor hobbies, outdoor work
- A personal history of skin cancer
- Skin cancer in a family member
- Numerous moles
What are the signs of skin cancer?
BCCs vary in appearance: while some look like a scaly, red mark on the skin, others form a lump with a rim surrounding a central crater. If left untreated, BCCs can eventually cause an ulcer—sometimes called a rodent ulcer. Most BCCs are painless, although they can sometimes be itchy or bleed. SCCs can also vary in appearance, but usually look like a scaly or crusty raised area of skin with a red, inflamed base. An SCC can grow slowly or rapidly, and is more serious than a BCC because there is a small risk that, if left untreated, it can spread or metastasise to other parts of the body.
Melanoma usually develops in or near a mole when the melanocytes become cancerous and multiply uncontrollably. Although melanoma is less common than NMSC, it is more serious because, if left untreated, the cancer can invade the surrounding skin and may also spread to other parts of the body such as the lymph nodes, liver and lungs Renal Association guidelines advise kidney transplant patients to check their skin regularly, and tell their doctor about any unusual change in appearance of the skin, such as:
- New lumps, spots, ulcers, scaly patches or moles that have recently appeared
- Marks (including moles) on the skin that have changed in shape, colour, texture or size
- Sores that do not heal
- Any areas on the skin that are itchy, painful or bleed
Your GP can refer urgently via the NHS two-week wait skin cancer referral pathway if you do not already have regular follow-up with a dermatologist. Eleanor advises that checking your skin is particularly important as you get older. “While it can be normal to develop new moles in your 20s or 30s, the older you are, the more you should be alert to new lumps, bumps or any change to an existing lesion (size or shape or colour or itching or bleeding). Transplant patients should have a low threshold to see their doctor and never think that they are bothering doctors if they are concerned about their skin,” she says.
Transplant patients should have a low threshold to see their doctor and never think that they are bothering doctors if they are concerned about their skin
How is skin cancer treated?
When diagnosing a possible skin cancer, the first step is a personal medical and family history. The dermatologist will ask how long the lesion has been present, how it has changed, and if it has produced any discharge or bleeding. The lesion will be palpated or felt and carefully examined using a dermatoscope (a handheld instrument rather like a magnifying glass).
Eleanor says: “Often the lesion is not skin cancer and is benign. That is good, because it’s great to be able to reassure a patient that the lesion is nothing to worry about. We would not generally remove a benign lump, such as a cyst or lipoma, because there are risks to surgery such as bleeding, infection and scarring.
“If I am concerned about a lesion, I either arrange to remove it completely or, if it is a large lump, I will remove a small section for a biopsy. Fortunately, BCC very rarely progresses, while less than one in ten SCCs will metastasise. There is a higher risk that melanoma will invade the surrounding skin and metastasise. This is why early diagnosis is so important. When patients present late, there is a high chance that melanoma has spread to lymph nodes, the lungs or liver and patients will need immunotherapy,” she adds.
How can skin cancer be prevented?
Since UV radiation is the main cause of skin cancer, protection against exposure to the sun, sunbeds or sun lamps is essential. This includes not only a high sun protection factor (SPF), broad-spectrum sunscreen, but also protective clothing.
Strictly avoiding sun exposure can reduce your vitamin D levels, so you may need to take a vitamin D supplement. NICE guidance advises that that all adults in the UK should take vitamin D between October and March to avoid deficiency. However, before buying any supplements, you should first ask your kidney doctor to check your vitamin D levels to avoid developing vitamin D toxicity or problems with your blood calcium level.
Advice on sun protection for kidney transplant recipients
- Never sunbathe and never use sunbeds or sunlamps
- Use a high SPF, broad-spectrum sunscreen of 50 with both UVB and UVA protection. Check for the UVA circle logo and use a sunscreen with 4 or 5 UVA stars as well as a high SPF
- Make applying sunscreen part of your morning bathroom routine. Apply every day to all exposed areas of skin including your central chest, backs of hands, and forearms
- Apply sunscreen before going out in the sun and reapply every two hours when outdoors, especially straight after swimming and toweldrying
- No sunscreen will provide 100% protection, so wear a broad-brimmed hat that shades your face, neck and ears, and tightly woven clothing, including long-sleeved shirts and trousers. UV protective swim- and beachwear is also available. Sunglasses are recommended as they help reduce your risk of cataracts by protecting your eyes from UV radiation
- Avoid the sun when the sun’s rays are strongest (11.00 am-3.00 pm). At all times, step into the shade before your skin has a chance to redden or burn
- Remember that there may be as much UV radiation on a cloudy day or during the winter as there is on a sunny summer day
Skin cancer surveillance: could do better
“Guidelines recommend that skin should be checked by a healthcare professional at least twice a year up to five years post-transplant followed by annual surveillance. Gold-standard surveillance is by a dermatologist with a special interest in skin cancer in a post-organ transplant dermatology surveillance clinic. However, comparatively few units are actually providing specialised clinics for monitoring organ transplant recipients,” says Eleanor.
A survey published in 2020 found wide variations in skin surveillance for kidney transplant patients in the UK. Of the 51 (86%) centres responding, 28 (55%) provided skin cancer surveillance posttransplantation, but in 18 (64%) of these, screening was by a non-skin cancer specialist. Only 21 (41%) units carried out a full skin examination. The 23 centres not providing skin cancer surveillance cited a range of limitations, including relying on patients’ reports of lesions (48%), lack of funding (48%), lack of training in skin surveillance (30%), time restraints in the clinic (30%), or they did not regard it as necessary in all patients (17%).
Gold-standard surveillance is by a dermatologist with a special interest in skin cancer in a post-organ transplant dermatology surveillance clinic
Eleanor concludes: “The situation is likely to be worse now because of Covid-19, since only telephone consultations were available for skin cancer surveillance for several months during the height of the pandemic in 2020. Patients are advised to monitor their skin for any changes, but they become less able as they get older. People cannot check their backs and the back of their legs, and they need to see someone with the right experience and expertise. That is why the post-transplant dermatology surveillance clinics are important. The problem in some centres may be lack of resources, but it means that some kidney transplant patients are not receiving the recommended skin surveillance they need to reduce their known risk of skin cancer and manage skin cancer early, which is crucial.”
This article appeared in the Summer 2021 issue of Kidney Matters magazine.
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