The article in one paragraph:

Skin cancer is one of the most common types of cancer that does not discriminate when it comes to age, gender, or skin type. Everyone can get it. Skin cancers are subdivided into two broad categories: Non-melanoma and melanoma skin cancers.

There are multiple risk factors for skin cancers, with the most preventible one being exposure to Ultra-Violet Rays (UVR). They come in all shapes, colours and sizes and some are more aggressive than others. Early detection and diagnosis is crucial as some of them can be fatal for their potential to spread.

Article objectives:

• Learn basic concepts about skin cancer;
• Learn what to look out for when assessing a skin lesion;
• Learn about what you can do to prevent skin cancer;

Questions answered in this article:

• How do you get skin cancer?
• What are the risk factors for skin cancer?
• What can I do to prevent skin cancer?
• How to know if a mole is cancerous?
• Is skin cancer hereditary?
• Can sunbeds cause skin cancer?
• How to recognise skin cancer?
• How to recognise melanoma?
• Is melanoma deadly?

Lies and myths you keep telling yourself about skin cancer:

• It’s just a mole!
• It’s normal if it changes;
• It’s normal if it crusts or bleeds;
• Sunbeds are safe;
• If I apply sunscreen it’s impossible to have skin cancer;

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Skin cancer can be very insidious since, in its early stages, it looks similar if not identical to an harmless mole (nevi). Moles change… that’s what they do. Up to the age of 40 years old new ones appear and existing ones tend to change. Since skin cancer can pose a real risk to health and life, it is crucial to be able to recognise and differentiate between a healthy, normal mole that it’s changing as per its physiological path, and a skin cancer.

Skin cancers are subdivided into two broad categories: Non-melanoma and melanoma skin cancers. So, let’s dive into these two categories.

Non-Melanoma Skin Cancer

Non melanoma skin cancer refers to all types of cancer affecting the skin that are not melanomas. Several skin cancers fall under this category, but in this article we will just focus on the two most common types: Basal Cell Carcinoma and Squamous Cell Carcinoma.

Basal Cell Carcinoma

Basal Cell Carcinoma (BCC) is the most common type of cancer in humans, which arises on sun-damaged skin. The good news about it is that it is a slow-growing tumour, metastases are rare and it’s rarely fatal. [1]

It can present itself as:

• An open, non-healing sore – this is the most common warning sign of BCC. A persistent sore that oozes, bleeds, and crusts for weeks.
• A pinkish growth – Growths often have an elevated and rounded border with an indentation in the centre.
• Red patch or irritated area of skin – Sometimes patches can crust or itch and are located on the face, shoulders, chest, legs and arms.
• A shiny nodule or bump – These are often pearly or translucent. Can be pink, red or white.
• A scar-like patch – scar with undefined borders. They look white, pale and waxy.

Squamous Cell Carcinoma

Squamous Cell Carcinoma (SCC) is the second most common type of non-melanoma skin cancer. It occurs on sun exposed areas like face, head, ears and nose. If left untreated it can spread throughout the body and in extreme cases it can also be life-threatening. [2]

It can present itself as:

• A persistent scaly patch – It is often red in colour with uneven borders. Often these patches will crust and bleed.
• An elevated growth with central depression – These growths are raised with an indentation to the centre. They grow rapidly in size and can also bleed and crust.
• Open sore – A sore that consistently crusts or bleeds and won’t heal over weeks.

Melanoma

Melanoma is no joke. In fact, it is the deadliest form of skin cancer. [3]. Survival rates are pretty high in its early stages as it can be successfully treated with surgery alone. However, survival rates can drastically drop once it metastasises. For this reason, early diagnosis and treatment are crucial for the best outcome. Melanoma has a sub-category known as Nodular Melanoma (NM), which behave and present themselves slightly differently than regular melanomas (read below in the section Nodular Melanoma to learn more).

What are the risk factors of melanoma?

The risk factors for melanoma re multi-factorial and shift between genetic susceptibility and environmental exposure.

Here’s a list of risk factors of melanoma [4]:

• UV rays exposure;
• History of sunburns;
• Family history of skin cancer;
• Personal history of melanoma or other skin cancers;
• Fair skin, freckling and light hair;
• Being male;
• Xeroderma Pigmentosum;
• Number of melanocytic nevi;

UV rays exposure

UV rays are an important, if not the most important, and modifiable environmental risk factor for developing malignant melanoma because of their genotoxic effect. [4].

Fun fact, the damage occurred as a consequence of uv exposure is cumulative and irreversible. It means that if you go out in the sun without SPF for one hour, the skin damage done in this one hour session will add up to the 30 minutes session you had yesterday, and to the 8 hours sunbathing session you had on holiday in Tenerife 3 years ago, and to the 2 hours session you had while you were learning to cycle in your childhood.

Studies concluded that intermittent sun exposure appears to be a major determinant of risk of melanoma [5].

History of sunburns

History of sunburns are associated with the highest risk of developing melanoma. [6] This may be due to the cumulative and irreversible sun damage caused by continues UV rays exposure, as discussed in the previous section.

Family history of skin cancer

Another strong risk factor for developing melanoma is a family history of melanoma. Studies have looked at the reasons as to why family history predisposes an individual to melanoma and they demonstrated the presence of a clear pattern of autosomal-dominant inheritance with multiple members affected in more than the first generation. [7].

The people who are mostly affected by melanoma that have an underlying genetic predisposition are usually young and up to 40 years old. [8].

Personal history of melanoma and other skin cancers

Previous melanomas, history of previous skin cancers or precursor lesions such as dysplastic skin nevi are all risk factors for developing melanoma. However, this category of risk factor seems to cause tumours that are superficially invasive and have a better prognosis. [8].

Fair skin, freckling and light hair

Red hair, fair skin, freckly skin, light eyes, inability to tan, and predisposition to burn all raise the risk of developing melanoma by approximately 50%; [9].

Being male

Studies show that males are approximately 1.5 times more lively to develop melanoma than female up to the age of 40 years old. After that, females seem to be more likely to develop melanoma than males. [10].

Xeroderma Pigmentosum

Xeroderma Pigmentosum (XP) is a rare, inherited condition that affects skin cells’ ability to repair damage to their DNA. Therefore, skin cells will have a hard time repairing the DNA damaged by the UV rays. (XP reference)

Number of melanocytic nevi

A meta-analysis showed that patient with more than 100 nevi (moles) have a 7 fold increased risk of melanoma. (nevi). Also, the presence of atypical or dysplastic nevi are associated with an increased risk too.

Diagnosis

The diagnosis of a melanoma is the result of a thorough medical history, which takes into account family medical history and sun exposure hygiene, and a physical examination with a magnification tool called Dermatoscope, which helps the clinical to appreciate the features of the mole in great details.

As a general screening tool, melanomas can be diagnosed with the simple mnemonic “A B C D E”.

A – (Asymmetry)

If you draw a line through the middle of the mole, the halves of a melanoma won’t match in size;

B – (Borders)

The borders of a melanoma tend to be irregular, crusty, uneven or notched.

C – (Color)

Healthy benign moles have an even homogenous colour. Watch out for discolouration that tend to the white or blue. That is bad.

D – (Diameter)

Melanomas can be larger than a pencil eraser (>5mm). Although they can also be smaller.

E – (Evolving)

When a mole changes in size, shape or colour or it begins to bleed or scab it is not a good sign.

Nodular Melanoma

Another category of melanoma is Nodular Melanoma (NM). They are the most aggressive type of melanoma. They can be a bit more tricky to detect as they do not follow the “ABCDE” screening rule and can look as benign lesions because they can appear more even in shape and colour. They are usually grey, blue, white, brown, tan, red or skin colour and often occurs in sun exposed areas. Because of its fast-growing nature in a downward direction, early detection is vital as it is usually invasive by the time of diagnosis.

How is Nodular Melanoma Diagnosed?

Nodular Melanoma do not follow the “ABCDE” screening tool like regular melanoma, but they can be detected with the “E F G” screening tool.

E – (Elevated)

Look out for an elevated bump that can vary in colour.

F – (Firm)

Nodular Melanoma are firm to touch and more even in shape.

G – (Growing)

Any lumps or bumps that is persistently growing.

How does the sun damage the skin?

This topic is discussed in depth here, where you can learn how ultraviolet rays (UVR) damage the skin leading to premature ageing and skin cancer.

Skin Cancer Prevention

Here’s what you can do to prevent skin cancer:

• Speak to your GP or dermatologist about your concerns and get regularly checked;
• Monitor any mole that looks suspicious by taking pictures every month with a measuring tape on the side – look out for any changes and promptly speak to your doctor if you notice any;
• If you are concerned about a mole or skin lesion and cannot get an appointment with your GP or dermatologist, try online services like Skindoc. Answer to some questions and upload your pictures to get those skin lesions checked by a dermatologist. They will get in touch with your GP and will also provide professional advice and reassurance.
• Apply sunscreen regularly. I cannot stress this point enough. Even on a cloudy day, even if you’re working in the office or at home and are close to a window, you need to apply it on regularly. To learn everything you need to know about sunscreens, go ahead and read this article.
• Avoid sunbeds – yes! they may cause skin cancer.
• Avoid sunbathing between 11am and 4pm.
• Get educated and informed! This is a major issue. Lack of information will lead you to ignore that suspicious skin lesions because, after all, “it’s just a mole”, and will also keep you in the same, old, harmful habits that increase the risk of skin cancer.

References

[1]. Dai J, Lin K, Huang Y, Lu Y, Chen WQ, Zhang XR, He BS, Pan YQ, Wang SK, Fan WX. Identification of critically carcinogenesis-related genes in basal cell carcinoma. Onco Targets Ther. 2018;11:6957-6967

[2]. Weber P, Tschandl P, Sinz C, Kittler H. Dermatoscopy of Neoplastic Skin Lesions: Recent Advances, Updates, and Revisions. Curr Treat Options Oncol. 2018 Sep 20;19(11):56.

[3]. Lauren E. Davis, et al. Current State of melanoma diagnosis and treatment. 2019.Cancer Biol Ther. 2019;20(11):1366-1379. doi: 10.1080/15384047.2019.1640032. Epub 2019 Aug 1.

[4]. M. Rastrelli et al., Melanoma: Epidemiology, Risk Factors, Pathogenesis, Diagnosis and Classification. 2014. In Vivo, 28(6) 1005-1011;

[5]. Sera  F,  Gandini  S,  Cattaruzza  MS,  Pasquini  P,  Picconi  O,  Boyle  P, Melchi  CF: Meta-analysis of risk factors for cutaneous melanoma: II. Sun exposure. Eur J Cancer 41: 45-60, 2015.

[6]. Elwood  JM, Jopson  J: Melanoma and sun exposure: an overview of published studies. Int J Cancer 73: 198-203, 1997

[7]. Tsao  H, Niendorf  K: Genetic testing in hereditary melanoma. J Am Acad Dermatol 51: 803-808, 2004.

[8]. Veierød  MB. et al.: A prospective study of pigmentation, sun exposure, and risk of cutaneous malignant melanoma in women. J Natl Cancer Inst 95: 1530-1538, 2003.

[9]. Friedman  RJ, at al.: Early detection of malignant melanoma: the role of physician examination and self-examination of the skin. CA Cancer J Clin 35: 130-151, 1985.

[10]. Markovic  SN, et al.: Melanoma Study Group of the Mayo Clinic Cancer Center: Malignant melanoma in the 21st century, part 1: epidemiology, risk factors, screening, prevention, and diagnosis. Mayo Clin Proc 3: 364-380, 2007.

[11]. The American Cancer Society. Risk Factors for Melanoma Skin Cancer. 2019. Accessed on 14.05.2022. Available on: https://www.cancer.org/cancer/melanoma-skin-cancer/causes-risks-prevention/risk-factors.html

[12]. Gandini  S, et al.: Meta-analysis of risk factors for cutaneous melanoma: I. Common and atypical naevi. Eur J Cancer 41: 28-44, 2005.