Skin cancer is the most common form of cancer in the U.S. – one in five Americans will develop skin cancer in the course of their lifetime.

“Skin cancer is the abnormal growth of skin cells – it most often develops on skin that has been exposed to the sun, but it can also form on areas of the skin that aren’t ordinarily exposed to sunlight,” explained Dr. Christine Cabell, a dermatologist who specializes in the diagnosis and treatment of pre-cancerous and cancerous skin lesions with Mohs micrographic surgery.

To some, skin cancer doesn’t seem as scary as other forms of cancer since its outside on your skin and treatment is as simple as removing the spot or mole.

“While early stage skin cancer may be limited to a spot or mark on your skin, untreated skin cancer, like many other forms of cancer, can advance and spread to other parts of the body,” Dr. Cabell said.

While some forms of skin cancer are less likely to spread than others, they still have the ability to grow larger and invade nearby tissues and organs, which can cause scarring, deformity or the loss of function in some parts of the body if left untreated.

There are three main types of skin cancer: basal cell skin cancers (basal cell carcinomas), squamous cell skin cancers (squamous cell carcinomas), and melanomas.

“Basal and squamous cell skin cancers are the most common skin cancer and are both found on parts of the body exposed to the sun, like the head and neck,” Dr. Cabell said. “These skin cancers are strongly related to sun exposure.”

Although it’s uncommon for these two types of skin cancer to grow into deeper layers of skin and spread to other parts of the body, it’s still possible.

“Melanomas, which develop in the pigment-making cells of the skin, aren’t as common as basal cell and squamous cell skin cancers and can be much more serious – melanoma is much more likely than other skin cancers to spread to other parts of the body if not caught early,” Dr. Cabell added.

Melanomas can develop anywhere on the body, even in places that are not normally exposed to the sun. In men, this type of skin cancer is more likely to start on the trunk, such as the chest and back. In women, melanoma is commonly found on the legs.

“Regardless of the type of skin cancer, they’re almost always curable in their early stages,” Dr. Cabell stressed. “That’s why it’s so important to regularly check your skin for any changes and to have your primary care physician or dermatologist to perform an annual skin cancer screening.”

Examine your skin often to look for new skin growths or changes in existing freckles, moles, bumps and birthmarks. Each type of skin cancer has many different appearances – look especially for a change of any kind, especially a mole, birthmark, beauty mark or any brown spot that:

  • Changes color
  • Changes texture
  • Increases in size or thickness
  • Has an irregular outline
  • Is bigger than 6 mm or a quarter inch – the size of a pencil eraser
  • Appears after age 21

Other warning signs to look for while examining your skin include an open sore that doesn’t heal within three weeks in addition to a spot or sore that continues to itch, hurt, scab, crust, erode or bleed.

“If you notice any of these changes, don’t ignore it, even if it doesn’t hurt,” Dr. Cabell advised. “Skin cancer can be painless yet dangerous at the same time. If you notice warning signs of skin cancer, see your doctor right away.”