What is skin cancer?
A skin cancer is a tumour in which there is uncontrolled proliferation of any of the skin cells, whereas the normal process of regeneration of skin involves replication of the cells in a controlled fashion. Each subtype of skin cancer has unique characteristics.
The most common forms of skin cancer are:
The term non-melanoma skin cancer refers to all types of skin cancer apart from melanoma. BCC and SCC are also called keratinocyte cancers.
Early, superficial skin cancers include:
- Superficial basal cell carcinoma
- Intraepidermal squamous cell carcinoma or Bowen disease (pre-cancerous, in-situ squamous cell carcinoma) and actinic keratoses
- Melanoma in situ.
Many different types of less common skin cancer are listed in the related information section at the bottom of this page.
Who gets skin cancer?
Skin cancer most commonly affects older adults but it can also affect younger adults, and rarely, children.
- Skin cancer tends to affect individuals with fair skin (Fitzpatrick skin phototype I, II and III), although people with darker skin can also develop skin cancer.
- People who have had a skin cancer have an increased risk of developing other skin cancers.
- A family history of skin cancer also increases risk.
What causes skin cancer?
The common forms of skin cancer listed above are related to exposure to ultraviolet radiation (from sunlight or tanning beds) and the effects of ageing. Other risks include:
- Smoking (especially for SCC)
- Human papillomavirus infection (genital warts), particularly for mucosal sites such as oral mucosa, lips and genitals
- Immune suppression, for example in patients who have received an organ transplant and are on azathioprine and/or ciclosporin
- Human immunodeficiency virus infection (HIV)
- Exposure to ionising radiation
- Exposure to certain chemicals, such as arsenic and coal tar
- Longstanding skin disease such as lichen sclerosus, lupus erythematosus, linear porokeratosis or cutaneous tuberculosis
- A longstanding wound or scar, eg, from thermal burn (a Marjolin ulcer).
Some skin cancers are due to genetic conditions, such as:
- Basal cell naevus syndrome
- Bazex–Dupré–Christol syndrome
- Bloom syndrome
- Brooke-Spiegler syndrome
- Cowden syndrome
- Dyskeratosis congenita
- Epidermolysis bullosa
- Epidermodysplasia verruciformis
- Familial atypical mole-melanoma syndrome (FAMM)
- Premature aging syndromes (progeria)
- Rothmund-Thomson syndrome
- Torré-Muir syndrome
- Xeroderma pigmentosum
What are the clinical features of skin cancer?
Skin cancers generally appear as a lump or nodule, an ulcer, or a changing lesion.
What are the complications of skin cancer?
Skin cancer can usually be treated and cured before complications occur. Signs of an advanced, aggressive or neglected skin cancer may include:
- Spread of the tumour to lymph glands and other organs such as liver and brain (metastasis).
How is skin cancer diagnosed?
Skin cancers are generally diagnosed clinically by a dermatologist or family doctor, when learning of an enlarging, crusting or bleeding lesion. The lesion will be inspected carefully, and ideally, a full skin examination will also be conducted.
- Dermatoscopy (a special magnifying light) may be used to confirm the diagnosis, to detect early skin cancers, and to exclude benign lesions.
- A partial skin biopsy may be taken in cases of suspected non-melanoma skin cancer to confirm the diagnosis.
- A complete excision is usually undertaken to make a diagnosis if melanoma is suspected, as partial biopsy can be misleading in melanocytic tumours.
- The diagnosis is confirmed in the laboratory by a histopathologist. It can take a few days for the report to be issued, or longer if special tests are required.
What is the differential diagnosis of skin cancer?
The differential diagnosis of skin cancer depends on the specific lesion.
What is the treatment for skin cancer?
Early treatment of a skin cancer is usually cures it. The majority of skin cancers are treated surgically, using local anaesthetic to numb the skin. Surgical techniques include:
Treatment options for superficial skin cancers include:
- Minor surgery including curettage and diathermy/cautery and electrosurgery
- Topical therapy such as fluorouracil cream, imiquimod cream or ingenol mebutate gel
- Photodynamic therapy (photosensitising cream plus light)
- Radiotherapy (x-ray treatment)
Treatment for advanced and metastatic melanoma may include:
- Systemic immunotherapy using ipilimumab or checkpoint inhibitors pembrolizumab or nivolumab
- Topical and intralesional immunotherapy for melanoma metastases
- Targeted therapy against BRAF mutations using vemurafenib or dabrafenib or MEK inhibition with trametinib
- Combination medications, such as cometinib.
Patients with skin cancer may be at increased risk of developing other skin cancers. They may be advised to:
- Practice careful sun protection, including regular application of sunscreens
- Learn and practice self skin examination
- Have regular skin checks
- Undergo digital dermatoscopic surveillance (mole mapping), especially if they have many moles or atypical moles
- Seek medical attention if they notice any changing or enlarging skin lesions
- Take nicotinamide (vitamin B3) to reduce the numbers of nonmelanoma skin cancers.
What is the outcome for skin cancer?
Most skin cancer can be completely cured with early treatment. Advanced skin cancers are more difficult to treat and can lead to death.