Skin cancer: What to look for and how to prevent it

Skin cancers are by far the most common types of cancer, accounting for one in three diagnosed globally. While some, such as non-melanoma skin cancers (including basal cell carcinoma and squamous cell carcinoma) are usually non-lethal, others, such as melanomas, can be more serious. Cases of both non-melanoma and melanoma skin cancers have been increasing over the past few decades, with the growth in melanomas of particular concern. By 2040, it’s estimated that nearly half a million cases of melanoma will be diagnosed every year, up by 62% from 2018.

May is skin cancer awareness month. To help increase understanding of this important disease, we highlight the main types of skin cancer, the warning signs, and practical steps you can take to reduce your risk of developing it.

What is skin cancer?

The skin can be broadly divided into three layers, the inner hypodermis (a fatty layer connecting your skin to your muscles and bones), the intermediate dermis (containing blood vessels, hair follicles, sweat glands, and other structures), and the outer epidermis (which protects these inner layers from the outside world). The epidermis primarily contains three types of skin cells, each of which can develop cancer:

• Squamous cells – thin flat cells that comprise most of the epidermis
• Basal cells – a layer of round cells found underneath the squamous cell layer
• Melanocytes – cells responsible for producing melanin, the pigment that gives skin its color and leads to tanning in response to sun exposure

Skin cancer can develop when the DNA of skin cells is damaged, typically through exposure to ultraviolet (UV) radiation from the sun or tanning beds, or other cancer-causing agents. This DNA damage may cause skin cells to grow uncontrollably, leading to cancer.

What are the main types of skin cancer?

The three main types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanomas.

Basal cell carcinomas are the most common form of skin cancer, making up approximately three-quarters of all skin cancer diagnoses. Although basal cell carcinomas are relatively unlikely to spread to other parts of the body, they can become locally invasive and grow in size, leading to damage to skin, tissue and bone. If detected early, most basal cell carcinomas are curable.

Squamous cell carcinomas account for approximately one-fifth of all skin cancers. Most squamous cell carcinomas are curable if caught early. However, if left untreated, they can grow into deeper layers of skin and spread to other parts of the body.

Melanomas are much less common than non-melanoma skin cancers. However, they are considered more dangerous as they are able to rapidly spread to other parts of the body if not treated early.  While melanomas make up just 2% of all skin cancer cases, invasive melanoma is responsible for around 80% of all skin cancer deaths.

Globally, more than 320,000 cases of melanoma were diagnosed in 2020, equivalent to approximately 4 in every 100,000 people. However, incidence rates vary widely by country, with those in some regions up to 10 times higher than the global average (Table 1). In the US and parts of Western Europe, approximately 15–20 in 100,000 people develop melanoma every year. The highest rates of melanoma can be found in Australia and New Zealand, where more than 30 in every 100,000 people develop the disease annually.

Table 1: Melanoma of the skin: Incidence rate by country

Source: World Health Organization GLOBOCAN 2020.

Spotting melanoma early makes a significant difference to survival outcomes. More than 99% of individuals whose melanoma was caught early will survive for at least a further five years after their diagnosis. However, five-year survival rates fall to 71% if the cancer has spread to the lymph nodes, and 32% if spread to other parts of the body.

Signs of skin cancer

Treatment for skin cancer is most effective when diagnosed early. It’s therefore important to be aware of the signs of skin cancer and consult with your doctor if you notice any unusual changes to your skin.

Basal cell carcinomas usually appear as a small, shiny pink or pearly-white lump that looks translucent or waxy. They can also look like a red, scaly patch containing brown or black pigment. The lump will grow bigger and may become crusty, bleed or develop into a painless ulcer.

Squamous cell carcinomas typically appear as a firm pink lump with a rough or crusted surface. The lump may hurt when touched, bleed easily, or develop into an ulcer.

Melanomas present as dark brown spots or growths on the skin, similar to moles or freckles. However, they take many different forms and can be more difficult to recognize. Approximately 20–30% of melanomas develop within existing moles, while 70–80% appear on normal skin. Unlike other moles, melanomas may have an irregular shape, may be larger in size, appear darker or lighter, or contain multiple colors. While some melanomas may itch or bleed, others may not display any of the typical warning signs. So, be vigilant for any new moles that appear unusual, grow or change.

Not all changes in the skin are signs of cancer. Speak with your doctor if you develop any skin abnormality that hasn’t healed after a few weeks.

Prevent skin cancer by protecting your skin

Skin cancer can occur anywhere on the body, but is most common in areas exposed to the sun, such as the arms, face, hands, and neck. While skin cancer is more common among individuals with lighter skin tones, people of all skin tones can develop skin cancer. Preventing overexposure to harmful UV radiation is therefore key to reducing your risk of developing skin cancer.

Top tips for skin cancer prevention:

• Avoid unnecessary exposure – more people develop skin cancer from indoor tanning than develop lung cancer from smoking. One of the easiest ways to reduce your risk of skin cancer is to avoid using sunbeds and sunlamps and the sun during the hottest times of the day, especially if you’re more prone to sunburn.
• Apply sunscreen – the National Cancer Institute recommend applying sunscreen with a sun protection factor (SPF) of at least 15, while some doctors advise products with an SPF over 30. Sunscreen products should be applied 30 minutes before venturing outdoors, and reapplied every 2 hours or after swimming or sweating.
• Wear a hat – wide brimmed hats are recommended, as baseball caps and sun visors are less able to protect all of your head, including your ears and neck.
• Wear sunglasses – glasses with UV filters will protect both your eyes and the skin around them.
• Wear long sleeves and pants – tightly-woven, dark clothing will act as a barrier, providing protection against UV rays.

While skin cancer isn’t always preventable, you can reduce the risk of developing it by taking sensible steps to protect your skin from the harmful effects of UV radiation. Staying vigilant for changes to your skin may help you spot cancer early, increasing your chance of successful treatment.

Why not share this blog with your friends and family to get others talking about skin cancer?