Skin cancer is the abnormal growth of skin cells that develops on the human skin whenever it’s exposed to the sun (ultraviolet). It can also emanate from other skin – part of the body that isn’t necessarily exposed to the sun. Unlike other types of cancer affecting humans, most cases of skin cancers are locally destructive cancerous i.e. malignant growth of the skin, originating from the superficial layer of the skin called the epidermis.

According to the World Health Organisation (W.H.O), there are basically two types of skin cancer; Non – melanoma skin cancer which comprises of Basal Cell Carcinomas and Squamous Cell Carcinomas; and also the Melanoma skin cancer. The Basal cell carcinoma is the most common form of skin cancer, followed by Squamous cell carcinoma (second most common) – originating from the skin cells. The third most common is the Melanoma skin cancer, which originates from the pigment – producing skin cells; although less common among humans but more dangerous than the other two.

In the year 2018, Melanoma of the skin is the 19th most commonly occurring cancer in men and women, involving over 300,000 new cases .Non-melanoma skin cancer is the 5th most commonly occurring cancer in men and women, with over 1 million diagnoses worldwide in 2018, although this is likely to be an underestimate. Currently, between 2 and 3 million non-melanoma skin cancers and 132,000 melanoma skin cancers occur globally each year.

Skin cancer affects people of all skin tones, including those with darker complexions. When melanoma occurs in people with dark skin tones, it's more likely to occur in areas not normally exposed to the sun, such as the palms of the hands and soles of the feet.

Is Skin Cancer Hereditary?

According to the World Health Organisation and Skin Cancer Foundation, it has been made known that skin cancers can’t be considered to be inherited since it is majorly caused by exposure to ultraviolet light exposure. Although not supporting the fact that genetics should be considered in skin cancer cases due to the fact that skin cancer is much common among poorly pigmented individuals, yet there are some very rare cases of genetic syndromes that have resulted in an increased number of skin cancers in people affected. This is usually caused by DNA mutations induced by ultraviolet light affecting cells of the epidermis.

Types of Skin Cancer

Early explained, there are two basic types of skin cancers; Non – melanoma skin cancer and Melanoma skin cancer.

Non – Melanoma Skin Cancers

The non – melanoma skin cancers comprise of Basal Cell Carcinomas; and the Squamous Cell Carcinomas. These two form of non – melanoma skin cancers are rarely harmful or dangerous but its treatment might cause skin disfiguring. Non – melanoma skin cancers are the most frequent on parts of the body that are commonly exposed to the suns i.e. ears, eyes, neck etc; with the ultraviolet light causing lasting damage.

• Basal Cell Carcinomas: This is a type of skin cancer that begins from the basal cells – a skin cell that produces new skin cells as the old ones die off. It is the most common form of skin cancer and the most frequently occurring form of all cancers. It often appears as a slight transparent bump on the skin.

Basal Cell Carcinomas occurrence is due to constant exposure to the ultraviolet light of the sun and could cause; and avoiding the sun (through the use of sunglasses; wearing of caps or long clothing) can help prevent it occurrence on an individual skin. Due to its nature of slow growth, basal cell carcinoma is usually curable and cause minimal damage to the skin once they are diagnosed and treated early.

• Squamous Cell Carcinomas: This is the second most common form of skin cancers. It develops in the squamous cells that make up the middle and outer layers of the human skin, characterized by the abnormal growth in the squamous cells. Although not life threatening, yet it can be quite aggressive if untreated, thus spreading to other layers of the skin causing serious complications.

Melanoma Skin Cancer

Melanoma skin cancer is the most serious and dangerous form of skin cancer; although far less prevalent than Non – melanoma skin cancer due to its ability to spread to other organs more rapidly if not treated at its early stage; it is the cause of major death from skin cancer. It develops from the melanocytes cell which is responsible for producing melanin.

The melanin is pigment that gives the skin its natural colour. There are two types of melanin: eumelanin and pheomelanin. When skin is exposed to ultraviolet radiation / light from the sun or tanning beds, it causes skin damage that triggers the melanocytes to produce more melanin, but only the eumelanin pigment attempts to protect the skin by causing the skin to darken or tan. Melanoma occurs when DNA damage from burning or tanning due to UV radiation triggers changes (mutations) in the melanocytes, resulting in uncontrolled cellular growth.

The risk of melanoma seems to be increasing in people under 40, especially women. Knowing the warning signs of skin cancer can help ensure that cancerous changes are detected and treated before the cancer has spread. Melanoma can be treated successfully if it is detected early.

Other Less Form of Skin Cancers

• Kaposi Sarcoma: This is a rare form of skin cancer that develops in the skin’s blood vessels, causing red or purple patches on the skin or mucous membranes. It occurs in people with weakened immune systems like AIDS.
• Merkel Cell Carcinoma: This is a rare type of skin cancer that usually appears as a flesh-colored or bluish-red nodule, often on your face, head or neck. It is quite aggressive with a high risk of recurring and spreading across the skin.
• Sebaceous Gland Carcinoma: This is an uncommon and aggressive skin cancer that begins in the oil glands of the skin. It is known to usually affect the eyelids.

Skin Cancer in Nigeria

Skin cancer is the most common malignancies in the world today with over three million non – melanoma skin cancers and 132,000 melanoma cases diagnosed every year.

Unlike other part of the world, skin cancer is less common in Nigeria, but it does occur among its citizens especially the albinos in the country. It is estimated that there are over 65,000 cases of skin cancer in Nigeria annually giving a projected annual incidence of 52 in 100,000.

Skin cancer is a major cause of morbidity and mortality in Albinos who develop premalignant and malignant lesions at a younger age and suffer from advanced skin cancers in the third to fourth decade of life. Unlike most form of skin cancer, Albinism is genetically inherited, and there are some quite numbers of them in the world. For Albinism in Nigeria, there is an estimated incidence of 1 to 15,000, especially in the Southern part of the country.

As stated earlier, lack of melanin and exposure to intense ultraviolet radiation increase the risk of developing skin cancer; therefore the lack of melanin in Albinos increases the risk of developing skin cancer by 1,000 fold as compared with the general Nigerian population.

Skin Cancer Worldwide Statistics: https://www.wcrf.org/dietandcancer/cancer-trends/skin-cancer-statistics

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