Skin cancer

The skin (also known as the integumentary system) is said to be the largest organ of the body, with a surface area of around 1.5–2m² in adults (Waugh and Grant, 2018). It also includes accessory organs; these are the glands, hair and nails, collectively called the appendages.

The skin is a multifunctional organ:

• offering protection against biological invasion, physical damage and ultraviolet radiation

• sensation is provided by nerve endings located in the skin

• the skin acts as a thermoregulator that is provided through sweating and the regulation of blood flow

• synthesis of vitamin D occurs in the skin

• the skin is to a small extent an excretory organ, as it excretes salts and small amounts of waste products in sweat

• the skin has an aesthetic and communication function

There are three layers of the skin: the epidermis, the dermis and the hypodermis. Skin health can have a significant impact on

There are a number of types of cell in the body and there are many different types of cancer that arise from the different cells. What all types of cancer have in common is that the cancer cells are abnormal and they multiply out of control. Cancer is a disease of the cells in the body.

There are two main types of skin cancer: melanoma and non-melanoma. Melanoma (this is also known as ‘malignant melanoma’) is less common than non-melanoma cancers; however, it is more dangerous. Non-melanoma skin cancers are primarily comprised of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). BCC is the most common and the least dangerous (Figure 1). 

A person's risk of developing cancer depends on various factors. These can include age, genetics and exposure to risk factors, including some potentially avoidable lifestyle factors.

The risk of melanoma increases with age; it is more common in older people. However, younger people can also develop melanoma.

Ultraviolet light (radiation) (from the sun or sunbeds) is the chief environmental factor that increases the risk of developing melanoma. Solar keratosis on the head and neck (patches of rough, dry skin) caused by over-exposure to sunlight puts people at an increased risk.

Skin colour and freckling can also be risk factors: those who are very fair-skinned, with fair or red hair, are more at risk of developing melanoma, as are people with a lot of freckles. Those with darker skins are still at risk of getting melanoma, but they have more natural protection against it. It is rare for black people in

Melanoma of the skin usually presents as a pigmented lesion on the skin. The cancer may also present after spreading to the regional lymph nodes or wider metastases. The melanoma may appear as a multicoloured nodule that grows vertically or in a circular spread of pigmentation larger than 1 cm (National Collaborating Centre for Cancer, 2015).

The borders of lesions are irregular and usually asymmetrical and bleeding may occur.

Squamous cell carcinoma typically presents as an indurated nodular keratinising or crusted tumour that can ulcerate, or it may present as an ulcer without evidence of keratinisation. Squamous cell carcinoma usually appears on the head and neck.

The typical features of basal cell carcinoma include: an ulcer with a raised, rolled edge; prominent fine blood vessels around a lesion; or a nodule on the skin (particularly pearly or waxy nodules).

To make a diagnosis, a full patient history is required. A total-body skin examination is essential. The Scottish Intercollegiate Guidelines Network (SIGN) (2016) recommends the ‘ABCDE’ checklist to identify signs of melanoma. Any of these features identified is an indication for referral:

• Asymmetry

• Border irregularity

• Colour: at least two different shades

• Diameter greater than 6 mm

• Evolutionary changes in colour, size, symmetry, surface characteristics, and symptoms

The ABCDE checklist is a good tool to use with patients to educate them about things to look out for. Patients should be made aware of non-mole changes too, such as a new growth or sore that will not heal, or one that hurts or itches.

The weighted 7-point checklist has been recommended by the National Institute for Health and Care Excellence (NICE, 2015) for routine use in UK general practice (Box 1). All suspicious pigmented skin lesions scoring 3 points or more should be referred urgently.

Box

Treatment options are provided on an individual basis after a detailed individual assessment is made. The multidisciplinary team works with the patient (and, if appropriate, family) to make an informed decision.

Surgery is the definitive treatment for early-stage melanoma, with medical management generally reserved for adjuvant treatment of advanced melanoma. The majority of patients are treated with wide local excision (surgery); radiotherapy may be the treatment of choice for those with in situ melanoma skin cancer. If a patient has metastatic melanoma, skin cancer radiotherapy, usually together with chemotherapy for palliative care, may be offered. Some patients may receive supportive care and observation only (NICE, 2010).

There are some kinds of skin cancer that cannot be prevented, as they are the result of genetic factors (non-modifiable lifestyle factors). The majority of skin cancers are caused by excessive exposure to the sun (modifiable lifestyle factors), so people should be encouraged to limit sun exposure by:

• remaining indoors or seeking the shade as much as possible between 11:00 and 15:00

• covering up with clothes and wearing a wide-brimmed hat when out in the sunshine

• liberally applying sunscreen of at least sun protection factor (SPF) 15 (SPF 30 for people with pale skin), which also has high ultraviolet A (UVA) protection

The use of sunscreen should not be seen as an alternative to avoiding the sun or covering up, it is used in addition. No sunscreen is 100% effective; it provides less protection than clothes or shade (Box 2). 

Box 2. Using sunscreen

References

Cancer Research UK. Risks and causes of melanoma. 2015. https://www.cancerresearchuk.org/about-cancer/melanoma/risks-causes (accessed 4 January 2019) 

Cancer Research UK. Skin Cancer. Types. 2017. https://www.cancerresearchuk.org/about-cancer/skin-cancer/types (accessed 4 January 2019) 

Cancer Research UK. Melanoma cancer statistics. 2018. https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/melanoma-skin-cancer (accessed 4 January 2019) 

National Collaborating Centre for Cancer. Suspected cancer: recognition and referral. Full guideline. 2015. https://www.nice.org.uk/guidance/ng12/evidence/full-guideline-pdf-2676000277 (accessed 10 January 2023) 

National Institute for Health and Care Excellence. Improving outcomes for people with skin tumours including melanoma (update): the management of low-risk basal cell carcinomas in the community (Partial Guidance Update). 2010. https://www.nice.org.uk/guidance/csg8 (accessed 10 January 2023) 

National Institute for Health and Care Excellence. Suspected cancer: recognition and referral. 2015. https://www.nice.org.uk/guidance/ng12/resources/suspected-cancer-recognition-and-referral-pdf-1837268071621 (accessed 4 January 2019) 

Scottish Intercollegiate Guidelines Network. Cutaneous melanoma. Quick Reference Guide 146. 2016. https://www.sign.ac.uk/assets/qrg146.pdf (accessed 4 January 2019) 

Waugh A, Grant A. Ross and Wilson Anatomy and Physiology (13th edn). Edinburgh: Elsevier; 2018