Introduction

The different forms of skin cancer are named after the type of skin cell from which they start. There are three main types of skin cancer:

basal cell carcinoma (BCCs)
squamous cell carcinoma of the skin (SCCs)
melanoma

The first two, BCCs and SCCs, along with a number of less common skin cancers, are known as non-melanoma skin cancer (NMSC) as they are different from melanoma. They are called non-melanoma skin cancers.^[1] There are other less common types of skin cancer. These include^[2]:

Merkel cell carcinoma
Kaposi’s sarcoma
T cell lymphoma of the skin
Sebaceous gland cancer

This paper is about skin cancers and is based on information from the various sources I have shown, either throughout the text (mostly as footnotes) or in a comprehensive list at the end.

What is Skin Cancer?

Cancer starts in the cells in our body. The cells are tiny building blocks that make up our organs and tissues. They receive signals from the body, telling them when to grow and when to divide to make new cells. This is how our bodies grow and heal. These cells can become old, damaged or no longer needed. When this happens, the cell gets a signal from the body to stop working and die. Sometimes these signals can go wrong, and the cell becomes abnormal. The abnormal cell may keep dividing to make more and more abnormal cells, which can form a lump called a tumour^.[3]

Not all tumours are cancerous. Doctors can tell if a tumour is cancer by taking a small sample of cells from it – a process called a biopsy, where the sample is looked at under a microscope for cancer cells.

A non-cancerous tumour (called a benign tumour) may grow but not spread elsewhere in the body. It usually only causes problems if it grows and presses on nearby organs. A tumour that is cancer (a malignant tumour) can grow into nearby tissue.

Sometimes cancer cells spread from where they started (the primary site) to other parts of the body. They can travel around the body in the blood or through lymph fluid which is part of the lymphatic system. When these cancer cells reach another part of the body, they may grow and form another tumour (this is called a secondary cancer or a metastasis). Some types of cancer start from blood cells. Abnormal cells can build up in the blood and sometimes the bone marrow, where blood cells are made. These types of cancer are sometimes called blood cancers.^[4]

The three main types of Skin Cancer

Basal Cell Carcinoma (BCCs)^[5]

Basal cell carcinoma is a type of skin cancer that most often develops on areas of skin exposed to the sun, such as the face. On brown and black skin, basal cell carcinoma often looks like a bump that’s brown or glossy black and has a rolled border. It is the most common form of skin cancer and the most frequently occurring form of all cancers. Most BCCs are curable and cause minimal damage when caught and treated early. Basal cell cancer grows slowly and can damage the tissue around it but is unlikely to spread to distant areas or result in death^[6].

It’s possible to have more than one basal cell cancer at any time, and having one does increase your risk of getting another. BCC is the most common type of skin cancer. About 75% of non-melanoma skin cancers are BCCs. They develop from basal cells found in the deepest part of the outer layer of the skin (the epidermis). There are different types of BCC, each of which can look and behave differently. They include^[7]:

nodular basal cell skin cancer (the most common sub-type)
superficial basal cell skin cancer
morphoeic basal cell skin cancer – also known as sclerosing or infiltrating basal cell skin cancer
pigmented basal cell skin cancer

Squamous Cell Carcinoma of the skin (SCCs)^[8]

Squamous cell carcinoma (aka cutaneous squamous-cell carcinoma (cSCC)) of the skin is a common form of skin cancer that develops in the squamous cells that make up the middle and outer layers of the skin. Squamous cell carcinoma of the skin is usually not life-threatening, although it can be aggressive. It usually presents itself as a hard lump with a scaly top but can also form an ulcer^[9]. Onset is often over months^[10]. Squamous-cell skin cancer is more likely to spread to distant areas than basal cell cancer^[11]. When confined to the outermost layer of the skin, a pre-cancerous or in-situ form of cSCC is known as Bowen’s disease^[12].

SCC is generally faster growing than basal cell cancers. About 20% of skin cancers are SCCs. They begin in cells called keratinocytes, which are found in the epidermis. Most SCCs develop on areas of skin exposed to the sun.

These areas include parts of the head, neck, and on the back of your hands and forearms. They can also develop on scars, areas of skin that have been burnt in the past, or that have been ulcerated for a long time. SCCs don’t often spread. If they do, it’s most often to the deeper layers of the skin. They can spread to nearby lymph nodes and other parts of the body, but this is unusual^.[13]

Melanoma^[14]

Melanoma is a cancer that develops from melanocytes, the skin cells that produce melanin pigment, which gives skin its colour. Melanomas often resemble moles and sometimes may arise from them. They can appear on any part of the body – even in areas not typically exposed to the sun. It is the most serious type of skin cancer that produces melanin and develops in the cells (melanocytes). Melanoma can also form in your eyes and, rarely, inside your body, such as in the nose, throat, mouth, and intestines. In women, they most commonly occur on the legs, while in men, they most commonly occur on the back^[15]. About 25% of melanomas develop from moles. Changes in a mole that can indicate melanoma include an increase in size, irregular edges, change in colour, itchiness, or skin breakdown^[16].

For melanomas and basal-cell cancers, exposure during childhood is particularly harmful. For squamous-cell skin cancers, total exposure, irrespective of when it occurs, is more important^[17]. Between 20% and 30% of melanomas develop from moles^[18]. People with lighter skin are at higher risk^[19].

Melanoma signs include^[20]:

A large brownish spot with darker speckles.
A mole that changes in colour, size or feel or that bleeds.
A small lesion with an irregular border and portions that appear red, pink, white, blue or blue-black.
A painful lesion that itches or burns.
Dark lesions on your palms, soles, fingertips or toes, or on mucous membranes lining your mouth, nose, vagina or anus.

Statistics

Advanced melanoma means the melanoma has spread from where it started to another part of the body. It’s also called stage 4 melanoma. For further detail, see the Cancer Research website^[21]. Melanoma skin cancer statistics^[22]provided by Cancer Research UK are:

The number of new cases each year is 16,744 new cases of melanoma skin cancer each year (2016-2018 average, UK).
The number of deaths from melanoma skin cancer is 2,341 (2017-2019, UK).
The percentage of patients who survive melanoma skin cancer for ten or more years is 87% (2013-2017, England).
Of all melanoma skin cancer cases, 86% were preventable (2015 UK).

In the US, nearly 70,000 Americans are diagnosed with melanoma each year, and it causes 8,700 deaths. Melanoma is now twice as common as it was two decades ago^[23].

Symptoms of Skin Cancer^[24]

Skin cancer — the abnormal growth of skin cells — most often develops on skin exposed to the sun. But it can also occur on areas of your skin that are not usually exposed to sunlight. You can reduce your risk of skin cancer by limiting or avoiding exposure to ultraviolet (UV) radiation. Checking your skin for suspicious changes can help detect skin cancer at its earliest stages. Early skin cancer detection gives you the greatest chance for successful skin cancer treatment^.[25]

Skin cancers are not all identical, and many initial symptoms are not immediately evident, but any unusual changes to your skin can be a warning sign. Being alert for changes to your skin may help you get a diagnosis earlier.

According to the World Health Organization (WHO), there are approximately 132,000 cases of melanoma and two to three million non-melanoma skin cancers diagnosed worldwide annually. Of non-melanoma skin cancers, about 80% are basal-cell cancers, and 20% are squamous-cell skin cancers.

It is important to note that:

new moles may indicate the presence of melanoma; but also
the moles you have had long-term, even since birth, can turn cancerous as you get older; and
you should check all moles on your body regularly, paying particular attention to their appearance and noting suspicious symptoms such as itching or oozing

The warning signs of skin cancer can vary. Signs of skin cancer can be subtle and difficult to identify, resulting in a delayed diagnosis. Awareness of the most typical warning signs is the best way to prevent skin cancer’s most serious or fatal outcomes by ensuring its earliest possible detection and diagnosis.

What to look for

Changes in Appearance: Changes in the appearance of a mole or lesion are the simplest way to identify that something may not be right. While melanoma is the least common form of skin cancer, it is also the deadliest. Melanoma often appears as regular moles but usually can be differentiated by some distinct characteristics. Use the ABCDE method to remember and detect these differences:
- Asymmetry: The shape of the mole or lesion does not have matching halves.
- Border: The edges of the mole or lesion are not clear. The colour seems ragged or blurred or may have spread into the surrounding skin.
- Colour: The colour is uneven. Different colours such as black, brown, tan, white, grey, pink, red or blue may be seen.
- Diameter: If the suspicious mole or lesion changes in size, there may be a problem. Increasing is more regular, but shrinking may also occur.
- Evolving: New moles or strange patches of skin, or clear changes of a mole, should be given early and serious attention.

The Australian-based Cancer Council has recently updated this recognition method and included the EFG diagnosis guidelines, which are:

Elevated moles that seem to stick out further on your skin.
Firm moles that are hard when you touch them.
Growing moles that are increasing in size rapidly.

Post-Mole-Removal changes to your skin: Although you may have had a mole removed, that does not ensure that you are no longer at risk of cancer in that area. Cancer cells can spread deep into the skin, far deeper than the mole you can see on the surface. Check the removal scar and look for any unusual spots or colours on or around the scar.
Fingernail and Toenail changes: Skin cancer can develop in places you may not expect, such as under your fingernails or toenails. These occurrences, often melanoma, can be noticed as dark spots or streaks below the nail. Keep an eye on your nails.
Persistent Pimples or Sores: Sometimes, skin cancer presents as a pink or red bump that looks like a pimple but does not disappear over time. Skin cancers can also appear as or cause sores and ulcers that will not heal.
Impaired Vision: Ocular Melanoma (OM) Melanoma can develop within the eyes and can be difficult to detect until its later stages, when symptoms usually emerge. Routine eye examinations are the most reliable way of detecting it at an early stage. It will eventually cause symptoms such as blurry vision, increased “floaters”, or dark or discoloured spots close to the iris. The likelihood of OM increases as people get older.
Scaly Patches: Dry, rough or scaly patches of skin can be a symptom of some types of skin cancer. If the patch of skin remains scaly or rough to the touch after applying moisturising products, it could be cancerous. It may be a lesion known as Actinic Keratosis (AK), which is a precursor to Squamous Cell Carcinoma (SCC). AKs usually appear on body parts that have more exposure to sunlight, including the scalp, and become more common with age.
Persistent Itching: If you are experiencing an itching sensation that will not stop, it may be caused by skin cancer. Often mistaken for bug bites, a mole or lesion that is newly itching or itching persistently or intensely, may have turned cancerous. Do not ignore this sensation, especially if it is accompanied by a change in appearance to the region of skin in question and speak to your doctor.

What causes Skin Cancer?

The two main causes of skin cancer are the sun’s harmful ultraviolet (UV) rays and the use of UV tanning beds.

Picture Credit: “Dermatologist” by kellinahandbasket is licensed under CC BY 2.0.

Most skin cancers are caused by damage that happens from exposure of the skin to the sun, either from sun exposure over a long period or from a history of getting sunburnt often. People with a history of sunburn or overexposure to the sun in childhood also have a greater risk of developing basal and squamous cell carcinoma. Because people live longer, they are exposed to more sun over their lifetimes.^[26] Other risk factors that play a role include^[27]:

Light skin colour
Age
Smoking tobacco
HPV infections increase the risk of squamous-cell skin cancer.
Some genetic syndromes including congenital melanocytic nevi syndrome, which is characterised by the presence of nevi (birthmarks or moles) of varying sizes either present at birth or appear within six months of birth. Nevi larger than 20 mm (3/4″) in size are at higher risk of becoming cancerous.
Chronic non-healing wounds. These are called Marjolin’s ulcers based on their appearance and can develop into squamous-cell skin cancer.
Ionizing radiation such as X-rays, environmental carcinogens, and artificial UV radiation (e.g. tanning beds). It is believed that tanning beds cause hundreds of thousands of basal and squamous-cell skin cancer. The World Health Organization now places people who use artificial tanning beds in its highest risk category for skin cancer. Alcohol consumption, specifically excessive drinking, increases the risk of sunburns.
The use of many immunosuppressive medications increases the risk of skin cancer. Cyclosporin A, a calcineurin inhibitor, for example, increases the risk approximately 200 times, and azathioprine about 60 times.
Deliberate exposure of sensitive skin not normally exposed to sunlight during alternative wellness behaviours such as perineum sunning.

The good news is that if skin cancer is caught early, your dermatologist can treat it with little or no scarring and high odds of eliminating it entirely.

Diagnosis and Treatment of Skin Cancer^[28]

In most cases, a suspicious mole will be surgically removed and closely examined to see whether it is cancerous. This process is known as a biopsy. A biopsy usually involves removing a small sample of tissue. But in cases of melanoma, the whole thing is usually removed at the outset.

A diagnosis of melanoma will usually begin with an examination of your skin. Some GPs take digital photographs of a suspected tumour so they can email them to a specialist dermatologist for assessment. As melanoma is a relatively rare condition, many GPs will only see a case every few years. It’s important to monitor your moles and return to your GP if you notice any changes. Taking photos to document any changes will help with diagnosis.

Often, you’ll be referred to a dermatology clinic for further testing if melanoma is suspected. You should see a specialist within two weeks of seeing your GP. A skin specialist (dermatologist) or plastic surgeon will examine the mole and the rest of your skin. They may remove the mole and send it for testing (biopsy) to check whether it’s cancerous. A biopsy is usually done using local anaesthetic to numb the area around the mole, so you will not feel any pain.

Skin Cancer Treatment^[29]

The doctor scrapes a little beyond the edge of the cancer to help remove all the cancer cells. The wound is then covered with ointment and a bandage. A scab will form over the area. The wound may take three to six weeks to heal. After surgery for BCCs and very early-stage SCCs, you may not need long-term follow-up care. But your doctor may want you to have regular check-ups for a time to ensure your treatment has been successful and the cancer has not returned. Having had skin cancer previously, there is a higher risk of:

developing it again in the same area (a recurrence).
getting another skin cancer somewhere else on your skin.

You should check your skin regularly for any new symptoms or changes that could be cancer. You could use a mirror if there are areas (like your back) you cannot see easily or ask a relative or friend to help.

If you have problems or notice any new symptoms in between check-ups, tell your doctor straightaway. After treatment for skin cancer, it is very important to protect your skin from the sun as it can help prevent further skin cancers. Being exposed to a small amount of sunshine without getting red or burning helps our bodies make vitamin D. If you are not exposed to the sun often, you can ask your dermatologist or GP to check your vitamin D levels and for advice on getting enough vitamin D.

Doctors try to minimise the effects of skin cancer treatments on your appearance. Many people have only minor scarring after treatment, but it may be more obvious for others.

If treatment has changed your appearance, you may feel differently about your body image. Although this often improves with time, you may feel self-conscious about your appearance. Camouflage make-up to cover a scar may help you to feel better about how the area affected looks. The British Association of Skin Camouflage^[30] provides advice about camouflage make-up.

Common Treatments^[31]

Common skin cancer treatments (used alone or in combination) include:

Cryotherapy: Cryotherapy uses liquid nitrogen to freeze skin cancer. The dead cells slough off after treatment. Pre-cancerous skin lesions (called actinic keratosis) and other small, early cancers limited to the skin’s top layer can be treated with this method.
Excisional surgery: This surgery involves removing the tumour and some surrounding healthy skin to be sure all the cancer cells have been removed.
Mohs surgery: With this procedure, the visible, raised area of the tumour is removed first. Then your surgeon uses a scalpel to remove a thin layer of skin cancer cells. The layer is examined under a microscope immediately after removal. Additional layers of tissue continue to be removed, one layer at a time until no more cancer cells are seen under the microscope. Mohs surgery removes only diseased tissue, saving as much surrounding normal tissue as possible. It’s most often used to treat basal cell and squamous cell cancers and near sensitive or cosmetically important areas, such as eyelids, ears, lips, forehead, scalp, fingers or genital area.
Curettage and electrodesiccation: The technique uses an instrument with a sharp looped edge to remove cancer cells as it scrapes across the tumour. The area is then treated with an electric needle to destroy any remaining cancer cells. This technique is often used for basal cell and squamous cell cancers and pre-cancerous skin tumours.
Chemotherapy and immunotherapy: Chemotherapy uses medications to kill cancer cells. Anti-cancer medications can be applied directly on the skin (topical chemotherapy) if limited to your skin’s top layer or provided through pills or an IV if the cancer has spread to other parts of your body. Immunotherapy uses your own body’s immune system to kill cancer cells.
Radiation therapy: Radiation therapy is a form of cancer treatment that uses radiation (strong beams of energy) to kill cancer cells or keep them from growing and dividing.
Photodynamic therapy: In this therapy, your skin is coated with medication, and a blue or red fluorescent light then activates the medication. Photodynamic therapy destroys pre-cancerous cells while leaving normal cells alone.
Shave biopsy: A sterile razor blade is used to “shave off” the abnormal-looking growth.
Punch biopsy: A special instrument called a punch or a trephine is used to remove a circle of tissue from the abnormal-looking growth. A hollow, circular scalpel is used to cut into a lesion on the skin. The instrument is turned clockwise and counter-clockwise to cut down about 4 mm to the layer of fatty tissue below the dermis. A small sample of tissue is removed to be checked under a microscope. Skin thickness differs in different parts of the body.
Incisional biopsy: A scalpel is used to remove part of a growth.
Excisional biopsy: A scalpel is used to remove the entire growth.

Checking your skin for Cancer

Skin cancers found and removed early are almost always curable. Finding them early can also prevent disfigurement and, in more serious cases, can be lifesaving. The NHS recommends you check your skin thoroughly once a month, although if you have previously had skin cancer, you may be required to check more frequently. You should consult your GP or dermatologist as soon as possible if you notice anything suspicious or feel worried or concerned about any potential abnormality.

The best way to begin regularly checking your skin is to learn where your moles, birthmarks, and other marks are and their usual look and feel to detect any changes over time. Generally speaking, if you notice any mole, lump, persistent sore or patch that is changing shape, growing, won’t heal, bleeding, crusting, itching or flaking – don’t delay, get it checked out. Often, the doctor may even detect the growth at a pre-cancerous stage – before it has become a full-blown skin cancer or penetrated below the surface of the skin^[32].

If you want detailed guidance on checking your skin for Cancer, visit the Cambridge University Hospitals website^[33].

Conclusion

In a troubling trend, the incidence of all types of cancers has been going up for years.

Harvard Health says the internet is full of warnings about things that cause cancer – antiperspirants, scented candles and bras, and stay clear of disposable chopsticks, microwaves, radon gas, and more. Scary or misleading claims are so plentiful that it’s hard to know which ones to take seriously – until now. Harvard has produced a free tool, The Cancer FactFinder, which you can access online.^[34] It was developed jointly by experts at the Zhu Family Center for Global Cancer Prevention at Harvard T.H. Chan School of Public Health and the Center for Cancer Equity and Engagement at the Dana-Farber/Harvard Cancer Center. It offers reliable information about whether certain cancer claims are true.

BAPRAS (The British Association of Plastic Reconstructive and Aesthetic Surgeons) says the evidence suggests that 70% of those over 55 will develop some form of skin cancer. A free BAPRAS booklet will help you understand what to look out for and better understand skin cancer and the treatments available^[35].

Nearly one in five people develop skin cancer sometime in their life. Almost all skin cancers can be cured if found and treated early. Treatments include excision, cryotherapy, Mohs surgery, chemotherapy and radiation. Check your skin for any changes in size, shape or colour of skin growths. If possible, try to see your dermatologist once a year for a professional skin check-up^[36].

Lastly, a few words about skin cancer terminology: throughout this paper, I have provided explanations for some of the skin cancer terms used by the medical community. One day, I will attempt to compile a comprehensive glossary, but in the meantime, here are some useful links:

Sources and Further Reading

https://en.wikipedia.org/wiki/Skin_cancer
https://www.cancerresearchuk.org/about-cancer/skin-cancer/types
https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/melanoma-skin-cancer
https://www.britishskinfoundation.org.uk/Blog/british-skin-foundation-skin-cancer-research
https://www.cuh.nhs.uk/our-services/dermatology/skin-cancer-service/how-to-check-your-skin-for-cancer/
https://www.nhs.uk/conditions/non-melanoma-skin-cancer/
https://www.nhs.uk/conditions/melanoma-skin-cancer/
https://www.macmillan.org.uk/cancer-information-and-support/skin-cancer/types-of-skin-cancer
https://www.macmillan.org.uk/cancer-information-and-support/melanoma
https://www.royalmarsden.nhs.uk/your-care/cancer-types/melanoma
https://www.skincancer.org/skin-cancer-information/
https://www.melanomauk.org.uk/Pages/FAQs/Category/faqs
https://www.mayoclinic.org/diseases-conditions/skin-cancer/symptoms-causes/syc-20377605
https://my.clevelandclinic.org/health/diseases/15818-skin-cancer
https://my.clevelandclinic.org/health/diseases/14391-melanoma
https://www.health.harvard.edu/topics/skin-cancer
https://www.hopkinsmedicine.org/health/conditions-and-diseases/melanoma
https://www.hopkinsmedicine.org/kimmel_cancer_center/cancers_we_treat/melanoma/
https://www.webmd.com/melanoma-skin-cancer/ss/skin-cancer-and-skin-lesions-overview
https://www.webmd.com/melanoma-skin-cancer/melanoma-guide/skin-cancer#1
BAPRAS Your guide to skin cancer, at: https://www.bapras.org.uk/docs/default-source/Patient-Information-Booklets/rcs_bapras_guide_skin_cancer-p.pdf
https://www.everydayhealth.com/skin-cancer/guide/
https://blog.carecircle.org/melanoma-skin-cancer/
https://www.aad.org/public/diseases/skin-cancer/types/common
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/melanoma
https://www.cancer.net/cancer-types/skin-cancer-non-melanoma/introduction
https://www.skincancer.org/skin-cancer-information/
https://www.skincancer.org/skin-cancer-information/skin-cancer-facts/
https://www.cancer.org/cancer/skin-cancer.html
https://www.solbari.co.uk/blogs/solbari-blog/10-skin-cancer-signs-you-should-be-aware-of
https://www.kingedwardvii.co.uk/health-hub/skin-cancer-types-and-symptoms-to-look-out-for
https://www.everydayhealth.com/skin-cancer/what-are-the-different-types-of-skin-cancer/
https://www.healthline.com/health/skin-cancer
https://www.cancer.org/cancer/skin-cancer/skin-cancer-image-gallery.html
Book: Dermatoscopy and Skin Cancer: A Handbook for hunters of skin cancer and melanoma, by Cliff Rosendahl and Aksana Marozava, published by Scion Publishing Ltd, 30^th April 2019, available at: https://www.amazon.co.uk/Dermatoscopy-Skin-Cancer-handbook-melanoma/dp/1911510339/
Book: ABC of Skin Cancer (ABC Series), by Sajjad Rajpar and Jerry Marsden, published by Wiley–Blackwell, 7^th April 2008, available at:https://www.amazon.co.uk/ABC-Skin-Cancer-Sajjad-Rajpar/dp/1405162198/
Book: Sunlight, Vitamin D and Skin Cancer: (Advances in Experimental Medicine and Biology, 1268), by Jörg Reichrath, published by Springer, 13^th September 2021, available at:https://www.amazon.co.uk/Sunlight-Vitamin-Skin-Cancer-Experimental/dp/3030462293/

[1] Source: https://en.wikipedia.org/wiki/Skin_cancer

[2] See: https://www.cancerresearchuk.org/about-cancer/skin-cancer/types for an explanation of these rarer non-melanoma cancers.

[3] Source and acknowledgement: https://www.macmillan.org.uk/cancer-information-and-support/skin-cancer#what_is_skin_cancer

[4] Ibid

[5] Sources: https://www.mayoclinic.org/diseases-conditions/basal-cell-carcinoma/symptoms-causes/syc-20354187, and https://www.skincancer.org/skin-cancer-information/basal-cell-carcinoma/

[6] Source: Cakir BÖ, Adamson P, Cingi C (November 2012). “Epidemiology and economic burden of nonmelanoma skin cancer”. Facial Plastic Surgery

[7] This paragraph, source: https://www.cancerresearchuk.org/about-cancer/skin-cancer/types

[8] Sources: https://www.mayoclinic.org/diseases-conditions/basal-cell-carcinoma/symptoms-causes/syc-20354187

[9] Source: Dunphy LM (2011). Primary Care: The Art and Science of Advanced Practice Nursing. F.A. Davis. p. 242. ISBN 9780803626478.

[10] Source: Ferri FF (2016). Ferri’s Clinical Advisor 2017 E-Book: 5 Books in 1. Elsevier Health Sciences. p. 1199. ISBN 9780323448383.

[11] Source: Cakir BÖ, Adamson P, Cingi C (November 2012). “Epidemiology and economic burden of nonmelanoma skin cancer”. Facial Plastic Surgery Clinics of North America. 20 (4): 419–422.

[12] Sources: (1) Yanofsky VR, Mercer SE, Phelps RG (2011). “Histopathological variants of cutaneous squamous cell carcinoma: a review”. Journal of Skin Cancer. 2011: 210813. This article incorporates text available under the CC BY-SA 3.0 license, and(2)Bath-Hextall FJ, Matin RN, Wilkinson D, Leonardi-Bee J (June 2013). “Interventions for cutaneous Bowen’s disease”. The Cochrane Database of Systematic Reviews. 2016 (6): CD007281.

[13] Source: https://www.cancerresearchuk.org/about-cancer/skin-cancer/types

[14] Source: https://www.mayoclinic.org/diseases-conditions/melanoma/symptoms-causes/syc-20374884

[15] Source: World Cancer Report (PDF). World Health Organization. 2014. pp. Chapter 5.14. ISBN 978-9283204299.

[16] Source: “Melanoma Treatment – for health professionals”. National Cancer Institute. June 26, 2015.

[17] Source: Gallagher RP, Lee TK, Bajdik CD, Borugian M (2010). “Ultraviolet radiation”. Chronic Diseases in Canada. 29 (Suppl 1): 5

[18] Source: World Cancer Report 2014. World Health Organization. 2014. pp. Chapter 5.14. ISBN 978-9283204299.

[19] Sources: (1) “Skin Cancer Treatment (PDQ®)”. NCI. 25 October 2013. Leiter U, Garbe C (2008). “Epidemiology of melanoma and nonmelanoma skin cancer–the role of sunlight”. Advances in Experimental Medicine and Biology. 624: 89–103. ISBN 978-0-387-77573-9.

[20] Source: https://www.mayoclinic.org/diseases-conditions/skin-cancer/symptoms-causes/syc-20377605

[21] At: https://www.cancerresearchuk.org/about-cancer/melanoma/advanced-melanoma accessed August 2022

[22] Source: https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/melanoma-skin-cancer

[23] Source: https://www.health.harvard.edu/topics/skin-cancer

[24] Source, mostly from: https://www.molesafe.com/skin-info/7-warning-signs-of-skin-cancer-to-pay-attention-to

[25] Source: https://www.mayoclinic.org/diseases-conditions/skin-cancer/symptoms-causes/syc-20377605

[26] Source: https://www.macmillan.org.uk/cancer-information-and-support/skin-cancer#are_you_worried_about

[27] Listed at: https://en.wikipedia.org/wiki/Skin_cancer#cite_note-UV2010-4

[28] Source: https://www.nhs.uk/conditions/melanoma-skin-cancer/diagnosis/ © Crown copyright acknowledged. See also: https://www.macmillan.org.uk/cancer-information-and-support/skin-cancer#tests_and_diagnosis

[29] Source: https://www.nhs.uk/conditions/melanoma-skin-cancer/treatment/ © Crown copyright acknowledged. There is a comprehensive description of the Curettage and electrosurgery procedure used to remove skin cancer at: https://myhealth.alberta.ca/Health/aftercareinformation/pages/conditions.aspx?hwid=abp7908 .

[30] At: https://skin-camouflage.net/scwp/

[31] Sources: https://www.skincancer.org/skin-cancer-information/ and https://www.cancer.gov/types/skin/patient/skin-treatment-pdq