90 percent of all cases of skin cancer are non-melanomas. Non-melanoma forms of skin cancer are much less aggressive than melanoma skin cancer (malignant melanoma), which is rarer. Non-melanoma skin cancers are mostly found in the upper layers of the skin without spreading, and – partly because their preliminary stages are well known – they can be caught early and therefore be treated easily.
Origins and causes
Non-melanoma skin cancer (basal cell carcinoma, squamous cell carcinoma) occurs when the skin is exposed to the sun or overly strong UV radiation, such as in sunbeds, without protection or for long periods of time. It primarily affects areas that get the most radiation:
- Head and forehead
- Ears
- Nose and lips
- Neck
- Lower arms and backs of hands
Men and women are equally affected. The disease cumulatively starts in the over-60s. People at higher risk of non-melanoma skin cancer are those who spend a lot of time outside, who often travel to sunny areas, or who do not use sun protection consistently. Those with pale skin who tend to sunburn easily are also more at risk.
However, UV radiation can inflict lasting damage on the skin cells even if you do not become sunburned. It can change the genetic material in the cells in the upper layers of the skin, which leads to non-melanoma skin cancer.
Frequency of non-melanoma skin cancer
Basal cell carcinoma is about four times more common than squamous cell carcinoma, which can be more serious.
Basal cell carcinoma (BCC; also known as basalioma)
Basal cell carcinoma is the commonest type of skin cancer worldwide. The carcinoma forms directly under the epidermis, between the basal cell layer and the dermis, along the hair follicle. Basal cell carcinoma grows slowly and only rarely forms metastases. If it goes unnoticed, however, it can grow downwards through the skin and affect bones and other tissues.
Symptoms of basal cell carcinoma
Basal cell carcinoma often appears at first as a small lump or hardened area on the nose, lips, ears, forehead, scalp or back of the hand. In its early stages it is barely visible, as there is no change in skin colour. It is not until later on that the tumour becomes noticeable to the naked eye as a:
- red, sometimes raised mark,
- change in the skin that looks like scarring,
- transparent, domed lump with fine blood vessels (solid BCC),
- hardened tissue (sclerosing BCC) or
- scaly patch of skin.
Other common symptoms of advanced BCC are patches of skin that are weeping, healing slowly or not at all; sore, crusty areas that bleed easily; and hardened lumps.
If you suspect BCC, you should see a dermatologist as soon as possible. If there is a family history of skin cancer or you have had multiple exposures to UV radiation, regular self-checks are advised to ensure early detection of basal cell carcinoma.
Squamous cell carcinoma (SCC; also known as squamous cell skin cancer or epidermoid carcinoma)
In squamous cell carcinoma, the damage to the skin cells is nearer to the surface, in the spinous layer, which is part of the epidermis. In contrast to basal cell carcinoma, squamous cell carcinoma is more likely to spread. Secondary tumours can form in other organs and nearby lymph nodes, although this is rare.
Symptoms of squamous cell carcinoma
The symptoms and appearance of SCC are similar to those of advanced basal cell carcinoma: patches of crusty, poorly healing skin on the face, head or backs of the hands, which weep and bleed easily.
Preliminary stages of squamous cell carcinoma
However, there are preliminary stages to squamous cell carcinoma that allow it to be recognised earlier.
Actinic keratosis
Areas of skin affected by actinic keratosis feel rough, generally remain skin-coloured and spread laterally on sun-exposed skin. In ten percent of cases, this precancerous condition will develop into a carcinoma, leading to SCC. So finding and treating actinic keratosis early on can prevent the development of non-melanoma skin cancer.
Bowen’s disease
Bowen’s disease looks similar to a rash or psoriasis. As a precancerous condition, it appears as changes to the skin that have clear borders but an irregular shape. Unlike actinic keratosis, these patches of skin may also occur in areas of the body that are not exposed to direct UV radiation. If left untreated, they lead to squamous cell carcinoma in around five percent of cases.
Indications of actinic keratosis or Bowen’s disease should be checked by a doctor in order to prevent a carcinoma forming. If signs of squamous cell carcinoma are already apparent, early diagnosis is key to its successful treatment.
Diagnosis
If non-melanoma skin cancer is suspected, the first step is for a dermatologist to feel the affected areas of skin and examine them with a dermatoscope. Then, if the dermatologist still suspects skin cancer, a biopsy will be carried out. The tissue sample will then be sent for further investigation in the laboratory.
Under some circumstances the area in question will be removed entirely during the initial examination. Further tests will subsequently be carried out to see whether it is non-melanoma skin cancer or not, and whether further treatment will be needed.
Treatment of non-melanoma skin cancer
If non-melanoma skin cancer is diagnosed, then it can be treated according to its characteristics and type. There is a variety of different treatment methods, which your specialist will discuss with you on an individual basis.
Surgical treatment
Basal cell carcinoma, squamous cell carcinoma and the preliminary stages of SCC can be surgically removed. Usually, the patch of skin that has changed will be cut out by the surgeon and then closed back up. During this process, in all cases a ‘safety margin’ of healthy tissue surrounding the area will be removed too, in case the cancerous cells have already spread outwards without being visible. If the region to be removed is larger or located in a challenging area, a plastic surgeon may create a flap of skin or carry out a skin graft to cover the wound.
Small, superficial carcinomas can also be removed using other methods:
- CO2 laser: A highly focused beam of light is used to remove the damaged cells.
- Curettage (scraping): The affected cells are removed with a small scraper (curette).
- Skin planing (dermabrasion): The diseased area of skin is worked upon with a special abrasive device.
Physical therapy
In some cases, surgical intervention is out of the question. The key factors here include the state of health and age of the person affected, as well as the position and size of the tumour. In such cases, or as a complement to surgery, various physical treatments may be used:
- Radiotherapy: The cancerous cells are destroyed with targeted low-energy X-rays. The surrounding tissue is left unharmed.
- Electrodesiccation: This treatment is only used with very small tumours. The affected tissue is destroyed with a heated electrode.
- Cryotherapy: Also known as ‘cold therapy’, this treatment uses liquid nitrogen to freeze the non-melanoma skin cancer. The cells die off and, after a few days, are rejected by the body independently.
Medication therapy
For some patients, such as older or very unwell patients, treatment with medication may be gentler. A distinction is made here between local and systemic therapeutic approaches. Local treatment involves applying creams and ointments directly onto the affected area of skin. They have different active ingredients that work in different ways to remove the tumour. Either they induce the body to produce its own immune response (imiquimod), or they destroy the cells themselves so that the body can get rid of them (5-fluorouracil and photodynamic therapy).
Prevention
In order to prevent non-melanoma skin cancer from developing in the first place, careful and consistent sun protection is needed. This means that, – e.g. even on cloudy days – sunscreen with UVA and UVB radiation protection should be applied, and clothing covering more sun-exposed areas i.e. the forehead, ears, neck, forearms and backs of the hand should be worn. You should also refrain from staying outside longer when the sun is at its strongest (between 11 am and 3 pm), avoid sunbathing for long periods of time and stay in the shade whenever possible.
Although non-melanoma skin cancer does not usually appear until fairly late in life, the actual UV damage is done to the skin much earlier, often even in childhood or adolescence. As the skin ‘remembers’ every instance of sun damage, the damage that occurs can later appear as a carcinoma. So, earlier and more consistent use of UV protection is the best preventive measure against squamous cell carcinoma and basal cell carcinoma, as well as malignant melanoma.
