- What is it?
What is skin cancer?
Skin cancer is the most common type of cancer, with over 100,000 new cases diagnosed in the UK each year. The disease is caused by damage to cells, usually by too much exposure to ultraviolet (UV) rays from the sun. The damage to the cells causes them to grow out of control and this leads to the formation of an abnormal mass of tissues called a tumour. Skin cancers usually develop in the outer layer of the skin, so the tumours are often detected at an early stage and can be treated successfully.
Types of skin cancer
The three most common forms of skin cancer are basal cell carcinoma, squamous cell carcinoma (together known as non-melanoma cancers) and melanoma.
Non-melanoma cancers are growths on the skin surface limited to a specific area that do not normally spread to other parts of the body.
Basal Cell Carcinoma
Basal cell carcinoma (BCC) is the most common human cancer and is the most common form of skin cancer, accounting for 80-90% of non-melanoma skin cancers.
BCCs are abnormal, uncontrolled growths or lesions that arise in the skin’s basal cells, which line the deepest layer of the epidermis (the outermost layer of the skin). BCCs often look like open sores, red patches, pink growths, shiny bumps, or scars.
Exposure to UV radiation (particularly in childhood and adolescence) is the major cause of BCC and tumours normally develop on sun-exposed areas of the skin, especially the face and neck. BCC occurs most often in white populations and is uncommon in darker skinned races. The closer Caucasians live to the equator, the greater the risk of developing BCC.
Other risk factors include having a fair complexion (red or blond hair, light eye colour), exposure to radiation, genetic predisposition (e.g. Gorlin’s syndrome) and a diet high in fat and low in vitamins.
Because exposure to the sun can cause BCC, people whose work requires long hours outside or people who spend their leisure time in the sun are particularly susceptible to developing BCC.
People who have had one BCC are more at risk of developing another one, either in the same place or somewhere else on the body, especially if they are male, more than 60 years old, had BCC on their torso or had a type of BCC called superficial.
In the past, more men had BCC than women but the number of women being diagnosed with BCC is rising.
Squamous Cell Carcinoma
Squamous cell carcinomas are much less common and also normally appear on sun-exposed areas of skin. These tumours are generally more severe than basal cell carcinomas and are more likely to spread to other areas of the body, although this is still uncommon.
Both types of non-melanoma cancers are usually treated by surgical removal of the tumour, however radiotherapy is also used in some cases.
Melanoma is the most severe form of skin cancer and causes the majority of deaths related to the disease. However, there is a good chance of cure if it is diagnosed at an early stage.
Melanomas are tumours that develop from melanocytes, the cells in the skin that produce a pigment called melanin. The role of melanin is to protect the skin from the UV rays of the sun. Melanomas normally develop from moles.
Moles are small areas of skin that are darker in colour than the surrounding skin. They are made up of a cluster of melanocytes. Moles are usually circular or oval with a smooth edge. The number of moles normally increases with age and people with fair skin often have more moles than people with darker skin.
The location of melanomas on the body can vary greatly and includes the head, neck, torso (chest, stomach and back) and legs. The most common area for men to develop tumours is on the torso, especially the back. For women, the area most at risk is the legs.
Although melanoma is the least common of the three forms of skin cancer, the number of cases is growing at a fast rate, higher than any other type of cancer. Melanoma is now the sixth most common cancer for men and women in the UK. The disease is particularly common in white people living in sunny climates and is more common in women than men. In adults the chance of developing the disease generally increases with age. Melanoma is rare in children. However, melanoma is the most common cancer in 15–34 year olds.
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- Metastatic Melanoma
Since melanomas are the most dangerous form of skin cancer, early diagnosis is important. A delay in diagnosis can lead to the disease spreading (becoming metastatic). A metastatic melanoma refers to a more advanced disease that has spread from its original site to deeper parts of the skin and eventually to other parts of the body, including the lymph nodes, lungs and liver. Approximately 20% of newly diagnosed cases of melanoma in the UK are metastatic. The prognosis for patients with metastatic melanoma is poor, although advances in treatments have recently been made.
Cancer is caused by damage to cells that results in the cells growing out of control and forming a tumour. Around 90% of melanomas are thought to be caused by exposure to ultraviolet (UV) light from the sun. A number of other risk factors have been identified that may increase the chance of getting the disease.
The most common risk factors are:
- Excessive exposure to UV light from the sun or sunbeds
- A history of sunburn
- Fair skin and freckles
- A high number of moles on the body
- Family history of melanoma
- Personal history of melanoma - once a melanoma has occurred there is an increased risk of a second occurrence
- Age - melanomas are more common in older than younger people
- Treatment with drugs for other conditions that weaken (compromise) the immune system
The early signs of a melanoma usually involve changes in the shape or colour of a mole. The ABCDE checklist can be used to identify potential warning signs to look out for in moles:
- Asymmetrical: melanomas have an irregular shape with two very different halves
- Border: normal moles have a smooth border, melanomas have a ragged, irregular border
- Colours: melanomas often change in colour or become patchy and have a mix of two or more colours
- Diameter: melanomas are larger than normal moles with a diameter greater than 6mm (1/4 inch)
- Elevated or enlarged: the melanoma is raised above the skin surface and often spreads around the original mole
Certain types of melanoma may also appear as a new growth on the skin, and any new skin change or mole, with any of the above warning signs, should be looked at by a GP.
If the GP thinks that a mole may be a melanoma they will refer the patient to a skin specialist (dermatologist). The dermatologist will look closely at the mole to see if it is a melanoma. Initially the mole will be examined and photographed. The dermatologist may use an instrument to magnify the area, which allows the mole to be seen more clearly. This is called dermatoscopy.
If the dermatologist diagnoses a melanoma then a second appointment will be made for the mole to be removed (excised). Following this procedure the removed mole is sent to a laboratory for analysis to confirm whether the growth is benign (non-cancerous) or malignant (contains cancerous cells). If the mole is malignant the patient will be referred for an operation to remove some of the tissue surrounding the mole in order to remove any abnormal cells that were left behind. This process reduces the risk of the melanoma returning.
If a malignant melanoma is diagnosed the doctor may do further tests to see if the cancer has spread. These may include an ultrasound scan and analysis of cells from the lymph nodes. Lymph nodes are small round organs that are part of the body’s lymphatic system. They are found widely throughout the body. The cells are removed from the lymph node using a fine needle and then examined by a specialist. Together these tests help the doctor to determine if melanoma cells have spread and the disease has become metastatic.
In some cases the lymph nodes may be examined in more detail. This involves using a radioactive substance or a blue dye (only small amounts of radioactivity are used in these tests). The radioactive substance or dye will pass into the sentinel lymph node (the sentinel lymph node is the lymph node closest to where the cancer started). The sentinel node is removed and examined in the laboratory for cancer cells. This procedure is called a sentinel node biopsy.
If melanoma cells are found in the lymph nodes, a full body X-ray called a CT scan is usually done to see if the cancer has spread to other parts of the body.
Other tests may also be performed to confirm the diagnosis of metastatic disease.
Treatment options for malignant melanoma
Surgery - The initial treatment for malignant melanoma involves surgically removing the mole as described in the section ondiagnosis. This procedure is normally performed under a local anaesthetic and allows the mole to be analysed in a laboratory and a diagnosis to be made.
If malignant melanoma is diagnosed, a second operation is performed to remove some of the tissue surrounding the affected area. The aim of this step is to remove any cancer cells surrounding the tumour.
This operation is called a wide local excision and is also normally performed under a local anaesthetic. In some instances, a general anaesthetic will be used when the doctor requires other diagnostic procedures to be performed, such as a sentinel node biopsy.
In most cases of malignant melanoma the treatment will be completed by the wide local excision. In some cases, however, the disease will have spread to other areas of the body (become metastatic) and will require more aggressive treatment.
Non surgical treatment for metastatic melanoma - Treatments for metastatic melanoma include chemotherapy, radiotherapy and biological therapies. In some cases surgical removal of tumours that have spread to other areas may also be performed, often in combination with drug treatment. The treatment decision depends on a number of factors, including how much and where the cancer has spread, the symptoms of the disease and treatments that have already been used.
Chemotherapy - Chemotherapy drugs work by stopping the growth of cancer cells. Unfortunately, chemotherapy can also kill normal cells and this can lead to side effects. Chemotherapy drugs are given as tablets or capsules that are swallowed or as a liquid that is injected into a vein. They are given as a single drug or sometimes as a combination of several drugs. To minimise severe side effects chemotherapy is often given for a few days and then not given again for several weeks. This treatment cycle is then repeated several times to achieve the most benefit.
The chemotherapy drug most commonly used to treat metastatic melanoma is called dacarbazine. This is sometimes used in combination with other chemotherapy drugs such as carmustine, vinblastine and cisplatin. In some patients, tumours will shrink when they are treated with chemotherapy. However, chemotherapy treatments for metastatic melanoma are not a cure and tumours can return.
Radiotherapy - Radiotherapy involves the use of high energy rays to damage and kill cancer cells. In metastatic melanoma, radiotherapy can help to shrink tumours and reduce symptoms. In some patients it is used after surgical removal of a melanoma to reduce the chance of the tumour returning.
Treatment is usually given once a day for several days, followed by a short rest period. In advanced cancer up to four treatment cycles can be given. The radiotherapy itself is not painful and side effects are normally red and sore skin.
Biological therapy - Biological therapies are treatments that stimulate the body’s own defences against melanoma or block one or more of the changes that make a cell cancerous. In the last few years several new treatments have been developed which provide new options for patients with metastatic melanoma. Like chemotherapy, these treatments do not cure metastatic melanoma. They can cause shrinkage of tumours and increase life expectancy.
Examples of biological therapies include vemurafenib, ipilimumab, interferon and interleukin 2.
Interferon and interleukin 2 - Interferon and interleukin 2 are naturally occurring substances in the body that stimulate the immune system to attack cells that the body recognises as abnormal, such as viruses, bacteria and cancer cells. Both may be used for treatment of advanced melanoma in some patients.
Several other treatments are undergoing clinical trials for use in metastatic melanoma.
Ipilimumab - Ipilimumab, also known as Yervoy, is a type of drug called a monoclonal antibody. Ipilimumab acts directly on the immune system by attaching to a protein called CTLA-4, which is found on the surface of one type of immune system cell (T-cells). CTLA-4 normally switches off T-cells and prevents them from attacking cancer cells. Ipilimumab works by blocking the CTLA-4 protein and thus enabling the T-cells to target and kill melanoma cells. Ipilimumab is given as a liquid injected into a vein (or infusion) once every 3 weeks for up to four infusions. Ipilimumab can help some adults with advanced melanoma by shrinking tumours and improving their life expectancy. Like all drugs, there are side effects (also called adverse events) associated with ipilimumab. Ipilimumab is most commonly associated with adverse reactions resulting from increased or excessive immune activity.
BRAF Inhibitors (e.g. vemurafenib, also known as Zelboraf) have recently been introduced as a treatment for adults with metastatic melanoma in the UK. The drugs, available as tablets, are a personalised medicine, meaning that they are designed to be used by people whose disease has a certain characteristic. In this case, BRAF inhibitors work in people that have a change (mutation) in a gene called BRAF V600. Approximately half the people with melanoma have this gene mutation.
The BRAF gene leads to the production of the BRAF protein which plays an important role in both normal and cancer cells. In normal cells the BRAF protein is part of a chain of molecules that tells cells how to grow and divide. This process is important for the cells to function properly. However, in people with the BRAF mutation the way in which the protein works is changed and this causes uncontrolled growth of cancer cells.
BRAF inhibitors work by attaching to the mutated BRAF protein and preventing it from working. This helps to slow down or stop the cancer cells from growing. BRAF inhibitors may slow the growth of melanomas and spread of the cancer, and improve life expectancy. Like all drugs, there are adverse events associated with BRAF inhibitors. For example, the most common adverse reactions associated with vemurafenib include joint pain (arthralgia), skin rash and sensitivity to sunlight (photosensitivity).
All of the medicines above can only be obtained by a prescription.
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- Basal Cell Carcinoma
BCCs can look very different as there are different types. These include:
Can have a pearl-like rim surrounding a central crater.
Can look like a scab that won’t heal or eventually become an ulcer.
Occur most frequently on the torso.
Look like a scaly red flat mark.
Unclear edges. Can look like a scar.
BCC that contains melanin and looks brown, black or blue.
This type of cancer is usually treatable and rarely life-threatening. It is usually slow growing and minimally invasive. Surgery cures most cases of BCC.
Treatment is much easier if BCC is found early. It is therefore important to see a doctor if you have marks on your skin that are growing, changing or bleeding and not completely healing.
In a small proportion of patients BCC can develop into advanced BCC, where surgery or radiotherapy is appropriate.
Advanced Basal Cell Carcinoma inappropriate for surgery or radiotherapy (aBCCi)
Whilst surgery cures most cases of BCC, in some instances there is progression to advanced BCCi where conventional treatment options such as surgery or radiotherapy are no longer appropriate. This includes locally advanced skin lesions or situations where the BCC has spread to other areas of the body and is causing noticeable symptoms - symptomatic metastatic BCC.
Several factors contribute to the development of advanced BCCi
Neglect or longstanding tumour
Large size (>2.5-3.0 cm)
Location on the mid face, nose and ears
Invasion near nerves or blood vessels
Locally advanced BCCi is not appropriate to be treated by surgery. There are several reasons why surgery may be considered inappropriate, these include:
• If the tumour has been removed before and has come back.
• If removing the tumour would cause significant damage or deformity. This can be the case if the tumour is very big or is close to a sensory organ.
Locally advanced BCCi is also no longer able to be treated by radiotherapy.
Metastasic BCC - Very rarely BCC's can spread to other areas of the body. This usually happens in cases where tumours have reoccurred or are of an aggressive histological type. It most commonly spreads to the surrounding lymph nodes, bone, lung or liver.
The goal of treatment of BCC is to completely remove the tumour whilst ensuring an acceptable cosmetic and functional outcome. Treatment of BCC can be divided into surgical and nonsurgical methods.
Surgical removal is the most effective treatment option for most BCCs. Usually this is done by surgical excision, curettage and cautery, cryosurgery and Moh’s micrographic surgery (MMS).
Surgical excision – This is performed under local anaesthetic. The BCC is cut away along with a surrounding border of normal skin. The skin is usually closed with a few stitches and the removed tissue is sent for microscopic examination to make sure that all the cancer cells have been removed. The main advantage of this technique is that the tissue can be checked to ensure all the tumour has been removed. Five year cure rates are 95% or better.
Curettage and cautery – After the skin is numbed with local anaesthetic, the BCC is scraped away using a curette (a sharp, ring-shaped instrument). Heat from the cautery destroys residual tumour cells and controls bleeding. This technique may be repeated several times to ensure all the cancer cells have been removed. While cure rates are also in the region of 95% or more, there is not enough tissue available to check microscopically if all the tumour has been removed. This technique is not suitable for high-risk tumours.
Cryosurgery – This involves the tumour tissue being destroyed by freezing with liquid nitrogen. There is no need for cutting or anaesthesia which makes the treatment suitable for patients with bleeding disorders or intolerance to anaesthesia. However there is no tissue available to check microscopically for any remaining cancer cells. The cure rate is similar to surgical excision and curettage and cautery.
Moh’s micrographic surgery – The tumour and a very thin layer of surrounding tissue is removed under local anaesthetic. The layer is then immediately checked under a microscope to see if any cancerous cells remain. If there is any tumour left in the thin layer of tissue, then another layer is taken and checked. This process is repeated until a tumour-free layer is identified under the microscope. The area is then usually covered with a skin graft. The advantage of this technique is that it preserves as much healthy tissue as possible. It tends to be reserved for BCCs unsuitable for simple excision, such as those in difficult areas e.g. around the eyes, nose lips or ears, recurrent tumours or those with characteristics that make them hard to remove. It has the highest cure rates of up to 99% for primary tumours and 95% for those that have reoccurred.
Radiotherapy – Beams of X-rays are directed at the area where the tumour is. Patients usually undergo several treatments a week for a few weeks. There is no need for cutting or anaesthesia and therefore this technique is useful for elderly patients and extensive tumours that are not appropriate for surgery. It is not recommended for younger patients as there can be long-term cosmetic problems. The five year cure rate is approximately 90%.
Photodynamic Therapy – This involves applying a cream to the BCC. The cream contains a photosensitizing agent. The cancer cells absorb the agent in the cream and become sensitive to certain wave-lengths of light. The next day, the area is exposed to light at the required wavelength and the cancer cells are destroyed. There is minimal damage to surrounding areas. This is best for superficial BCCs and has a variable cure rate – likely between 70 and 90%.
Topical Medications (creams)
Imiquimod is a cream that is rubbed into the tumour five times a week for six weeks. It is an immune response modifier which means it works by stimulating the body’s immune system. It is only approved to be used on superficial BCCs and has a cure rate of 80-90%.
Similarly fluorouracil can also be applied to superficial BCCs with similar cure rates to imiquimod.
Vismodegib – This is the first medicine for advanced BCCi (locally advanced lesions which are inappropriate for surgery or radiotherapy or symptomatic metastatic). It can only be used in patients with advanced disease.
All of the non surgical treatments above can only be obtained by a prescription.
Even though BCCs can usually be cured when diagnosed and treated early, it is still better to prevent them. These tips may reduce the risk of developing BCC.
- Stay in the shade, especially between 10 and 4 when the sun’s rays are at their strongest
- Do not burn
- Avoid tanning and sunbeds
- Cover up with clothing, hats and sunglasses
- Use sunscreen every day and reapply regularly, especially after swimming or excessive sweating
- Protect babies and children from the sun
- Check skin regularly and see a doctor if you notice a change to a mole or any patch of skin
Cancer research UK
Macmillan Cancer Support
British Skin Foundation
British Association of Dermatologists Basal Cell Carcinoma Patient Information Leaflet
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