What is skin cancer?
Skin cancer is damage to the DNA inside skin cells, causing them to mutate into cancerous cells. These cancers, also known as carcinomas and melanomas, continue to grow and often spread to other parts of the body if they are not removed quickly. There are different types of skin cell, each with their own specific type of cancer. These cancers (and the cells they affect) are known as basal cell carcinomas (basal cells), squamous cell carcinomas (squamous cells), and melanoma (melanocytes). As a result of their differences in location and skin type, these cancers look and grow differently from one another.
What types of skin cancer are there?
There are three main common types of skin cancer (basal cell carcinomas, squamous cell carcinomas, melanomas) and there are other, rare types (merkel cell carcinoma, kaposi sarcoma, cutaneous t-cell lymphoma, sebaceous gland carcinoma and dermatofibrosarcoma protuberans).
What does skin cancer look like?
Each of the three main types of skin cancer can appear differently, though there are often similarities as well. One of the most common ways of recognising a skin cancer is in the appearance of a new skin mark, such as a mole. Similarly, changes in shape, size or colour to an existing mole is also a common sign of skin cancer.
Specifically, skin cancers mostly appear as follows:
Basal cell carcinomas
Basal cell carcinomas are often dry, hard and scaly areas that are noticeably red (often with pearly nodules). These lesions (which can also be brown, blue or black) are mostly found in nodular basal cell carcinomas. Basal cell carcinomas often looks like a sore that does not completely heal (which occurs when the carcinoma ulcerates as it grows) and as a result of their slower rate of growth are the most treatable form of skin cancer.
Squamous cell carcinomas
Squamous cell carcinomas are not as dangerous as melanomas but may spread to other parts of the body if not treated. They grow over a period of months, appearing on areas of skin most exposed to sunlight (such as the face, lips, neck and back). While they are also similar looking to basal cell carcinomas – often red and scaly, ulcerated or crusty – they are more likely to spread than basal cell carcinoma. The cancerous lesions may also appear any number ways, and blood vessels are often present at the edge of the lesion.
Superficial spreading melanomas are one of the most commonly-diagnosed forms of melanoma and can develop in any region of the skin. They are usually raised around the edges and can be any number of colours, from red and pink, to brown, grey or blue.
Acral lentiginous lesions usually develop on the hands and feet and are characterised by flat tumours that are usually dark in colour – brown or black.
Lentigo maligna melanomas are mostly found on the face and are recognisable by an irregular border. They are usually tan to brown in colour.
Nodular melanomas Nodular melanomas are highly dangerous and looks different to common melanomas. Their appearance is more raised and they are often brown, red or pink in colour. Nodular melanomas can be life-threatening if not detected and removed promptly.
What causes skin cancer?
Skin cancer is primarily caused by exposure to UV radiation, present in sunlight. For complete protection against damage from the sun, the skin needs to be protected from UVA, UVB and IRA (infrared light). Roughly 35% of solar energy is IRA, which generates the heat we feel, though UV radiation is both invisible and not physically noticeable in the same way IRA is. The fairer the skin, the more susceptible it is to sun damage and skin cancer. People with Nordic and Celt blood, fair skin, freckles or fair/red hair are particularly prone to skin cancers. People with very dark skin, such as dark Asians and Africans, have more melanin in their skin which offers a natural protection from the sun, though there are other causes of skin cancer as well such as tobacco, HPV infections and some genetic conditions.
What are the signs of skin cancer?
It is very important to note that pain and bleeding are usually much later symptoms of skin cancers, and therefore an absence of pain or bleeding is not a sign that there is no problem. There are a variety of different skin cancer signs. In the case where a mole is pre-existing, changes to its size, colour or shape (or the shape of its border) indicate the presence of skin cancer. If a new mole has appeared out of nowhere, this is also cause for concern as it can indicate the presence of skin cancer. Other physical indicators are areas of skin that do not heal, ulceration and discolouration.
How do I protect myself from skin cancer?
The most effective way to prevent skin cancer is to avoid getting too much direct sunlight, particularly during the hottest hours of 10am-5pm. Being indoors is obviously maximum protection, but outdoors it is advisable to seek shade (under a tree, or using an umbrella for instance). If contact with direct sunlight is unavoidable, using sunscreen is highly recommended to help reduce the risk of skin cancer. Sunscreen comes with an SPF value that indicates its strength against UV radiation. SPF 30+ only allows 1/30th of UV radiation to reach the skin, for example. The paler your skin, the more protection you will need to prevent sunburn (and the risk of cancer).
For the purpose of measuring response to sunburn, there are seven different skin types: Type 1 and 2 (such as people with Nordic or Celtic blood, fair and red-headed people) burn easily, tan only slightly and have a high cancer risk. People with type 1 and 2 should always use a minimum SPF of 30, and are advised to spend as little time in the summer sun as possible. Skin types 3 and 4 have a moderate to low cancer risk, encompassing the vast majority of Europeans, Mediterraneans and paler-skinned Asians. People with type 3 or 4 should use a minimum SPF of 15, though 30 is still safer. Skin types 5-7 are predominantly dark Asians and Africans, who have a very low cancer risk and rarely burn due to their high levels of melanin. These skin types are very resistant to sunburn, though sunscreen may still help prevent skin ageing in such cases.
How is skin cancer treated?
Most skin cancers require surgical removal. This is to fully remove the cancer and stop it from spreading to other parts of the body. If the disease is in the advanced stages there may be some further action required.
With squamous cell and basal cell carcinomas, a safe margin of healthy tissue is removed to try and prevent any recurrence of the cancer at the original area. This tissue is usually taken when the carcinoma is removed. In cases of recurrence, particularly with basal cell carcinomas, a technique known as Moh's surgery may be employed. This is a method of obtaining complete margin control during removal of a skin cancer which allows for a very narrow surgical margin and a high cure rate.
Melanomas are usually assessed microscopically, the results of which dictate further treatment. Sometimes, a further excision of the skin is conducted (such as sentinel lymph node biopsy) to use for more detailed examinations.
Very superficial basal cell carcinomas and pre malignant conditions such as Bowen's disease and Actinic Keratoses can also be treated with other means such as topical creams (5 FluroUracil, Imiquamod, Solaraze), cryotherapy (freezing with liquid nitrogen) or photodynamic therapy (light activation of a topical cream)
How common is skin cancer?
The Cancer Council Australia report that two in three Australians will be diagnosed with skin cancer by the time they are 70, and that the incidence of skin cancer in Australia has continued to rise (melanoma diagnoses increased by around 60%, and non-melanoma diagnoses increased by 14%) within the last 30 years.
Non-melanoma skin cancer is the most common type of skin cancer, occurring twice as frequently in men than in women. Over 434,000 people are treated for one or more non-melanoma skin cancers in Australia each year.
Excluding non-melanoma skin cancer, melanoma is the third most common cancer in both Australian women and men, and the most common cancer in Australians aged 15-44 years. Over 11,000 Australians are diagnosed per year.
Around 2,000 people die from skin cancer in Australia, with melanomas accounting for 1,500 of those cases. The five-year relative survival rate for melanoma is 90% for Australian men and 94% for Australian women.
What are the survival rates for skin cancer?
Survival depends on the type and stage of the cancer. Generally, basal cell carcinomas rarely spread and (once removed and confirmed microscopically) can be considered 'cured'. Squamous carcinomas also rarely spread to the local lymph nodes, giving them a high survival rate, but as spreading is always possible it is necessary for careful follow-ups.
Melanomas can recur, depending upon their stage at first diagnosis. The five-year relative survival rate for melanoma is 90% for Australian men and 94% for Australian women. Thin melanomas (less than 0.76mm) are associated with an excellent prognosis but thicker melanomas can be associated with lymph node involvement (often only detected by sentinel lymph node biopsy).
What is Sentinel Node Biopsy?
Having completed a biopsy on a malignant melanoma, a surgeon can arrange to visualise the path taken through the lymphatic system that is affected by the melanoma. As the lymphatic system drains the area of a melanoma, cancer cells can become trapped in the lymph node. By a combination of coloured dye, imaging and a short acting low-dose radioactive tracer, it is possible to identify the 'sentinel node' and then proceed to check it for the presence of cancer cells.
Is skin cancer treated with radiotherapy?
Only under certain circumstances, but usually no. These exceptional circumstances can include situations where basal cell carcinomas can not be removed fully (or without the need for further, potentially mutilating, surgery) or are in awkward sites on the body that make surgery too difficult, risky, or potentially harmful. In such cases, radiotherapy may be considered.
Also, while it is very uncommon for radiotherapy to be an initial treatment of melanoma, it is useful as a treatment in more advanced stages of the disease.
Is skin cancer treated with chemotherapy?
It is very unlikely that chemotherapy will be recommended, as most skin cancers are treated solely by surgery. Chemotherapy is still in trial and use for treating advanced stages of melanoma, but would not usually be recommended to treat the disease.
Do sunbeds increase the risk of skin cancer?
Yes they do, and as such they are not recommended. Any unnecessary absorption of UV light by the skin not only increases the chance of cancer, it will cause premature aging and deterioration.