Skin Cancer - Symptoms & Causes

What is skin cancer?

Skin cancer involves the abnormal growth of skin cells. It is the result of mutation in the DNA of the skin cells, and is mainly caused by overexposure to the ultraviolet (UV) rays of the sun. However, skin areas that are not usually exposed to sunlight can also develop skin cancer.

If detected early, skin cancer can be successfully treated.

Types of skin cancer

There are 4 main types of skin cancer:

Basal cell carcinoma

It is the most common form of skin cancer. It arises from the basal cells present in the epidermis of the skin (the outermost layer of the skin). Basal cell carcinoma usually develops on skin that is exposed to sunlight, such as the skin of the scalp, face, neck, ears, shoulders and back. It rarely spreads to other parts, but can be fatal if it does.

Squamous cell carcinoma

It is the second most common type of skin cancer. It arises from the squamous cells present in the epidermis of the skin. It usually develops on sun-exposed areas such as the skin of scalp, face, ears, neck and hands. It can also develop on skin that has been damaged by chemicals, burned, or exposed to X-rays. If not treated early, squamous cell carcinoma can grow deep into the skin and spread.


It is considered the most dangerous form of skin cancer. It originates from the cells that give colour to your skin, known as melanocytes. It may develop from an existing mole or one that is newly formed.

Melanoma usually gets triggered due to UV rays, or tanning lamps and beds. It is curable if detected and treated early.

In the West, melanoma appears commonly on the skin, especially over sun-exposed areas of the skin. In Asia, melanoma develops more commonly in the hands and feet.

Merkel cell carcinoma

It is a rare skin cancer that is highly aggressive in nature, growing at a fast rate. It is found on the head, neck and trunk region just below the skin, and in hair follicles.

Some other rare types of skin cancer are cutaneous T-cell lymphoma, dermatofibrosarcoma protuberans, Kaposi’s sarcoma, microcystic adnexal tumours, and sebaceous carcinoma.

What are the symptoms of skin cancer?

Symptoms of skin cancer vary according to the type of skin cancer.

Signs and symptoms of basal cell carcinoma

  • A waxy, pearly, red or pink bump
  • A dry rough crust on the skin that may bleed, heal and recur
  • A flat, pinkish-red or brown scar-like lesion
  • A reddish or pinkish raised patch that may itch or crust but does not hurt

Signs and symptoms of squamous cell carcinoma

  • A raised patch with a rough or scaly surface and a central indentation
  • A wart-like growth
  • An open sore that lasts for weeks
  • A persistent, scaly red spot with uneven borders that may bleed easily

Signs and symptoms of melanoma

  • Asymmetrical lesion
  • Borders are irregular
  • Color is uneven
  • Diameter is more than 6mm
  • Evolves over time

Signs and symptoms of Merkel cell carcinoma

  • Red, pink or blue bumps on the skin
  • Shiny, firm and painless bumps

Skin changes could be warning signs of skin cancer or another underlying health condition. If you have concerns, make an appointment with your doctor to determine the cause of your skin changes.

What causes skin cancer?

The main cause of skin cancer is overexposure to sunlight, especially if it causes sunburn or blistering. The UV rays from the sun damage the DNA of skin cells, resulting in skin cancer.

Frequent skin exposure to UV tanning beds and lamps, as well as chemicals such as coal and tar, may also lead to skin cancer.

What are the risk factors for skin cancer?

It is possible for skin cancer to also develop on skin that is not usually exposed to sun. There are a number of risk factors that may contribute to skin cancer:

  • Fair skin, blond or red hair, light-coloured eyes
  • Skin that sunburns or freckles easily
  • History of abnormal moles
  • Precancerous skin lesions that are rough, scaly and vary in colour
  • A weakened immune system due to certain diseases, drugs or organ transplantation
  • Previous treatment with radiation therapy
  • Certain inherited syndromes

How do you prevent skin cancer?

There is no proven way to prevent skin cancer. However, you can adopt the following habits to possibly reduce the risk of skin cancer:

  • Apply a broad-spectrum sunscreen with a skin protection factor of at least 30 on all exposed parts throughout the year
  • Avoid tanning beds and lamps
  • Use sunglasses with UV protection
  • Avoid recreational sunbathing
  • Examine your skin regularly for any changes or new growths
This page has been reviewed by our medical content reviewers.

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