Skin Cancer

Skin cancer — the abnormal growth of skin cells — most often develops on skin exposed to the sun, such as the scalp, face, lips, ears, neck, chest, arms, and hands. But this common form of cancer can also occur on areas of your skin not ordinarily exposed to sunlight.
Skin cancer begins in your skin’s top layer called the epidermis. The epidermis contains three main types of cells: basal cells, squamous cells, and melanocytes. In which of these cells cancer cells begin to form determines the type of skin cancer a person has. The three major types of skin cancer — basal cell carcinoma, squamous cell carcinoma, and melanoma.

Basal cell carcinoma
Basal cell carcinoma usually occurs in sun-exposed areas of your body, such as your neck or face. It may appear as:

  • A pearly or waxy bump
  • A flat, flesh-colored or brown scar-like lesion

Squamous cell carcinoma
Most often, squamous cell carcinoma occurs in sun-exposed areas of your body, such as your face, ears, and hands. People with darker skin are more likely to develop squamous cell carcinoma on areas that aren’t often exposed to the sun. Squamous cell carcinoma may appear as:

  • A firm, red nodule
  • A flat lesion with a scaly, crusted surface

Melanoma, the most deadly form of skin cancer, can develop anywhere on your body, in otherwise normal skin or in an existing mole that becomes cancerous. Melanoma most often appears on the face or the trunk of affected men. In women, this type of cancer most often develops on the lower legs. In both men and women, melanoma can occur on skin that hasn’t been exposed to the sun.

The most important warning sign for melanoma is a new spot that changes in size, shape, or color. Another warning sign is a spot that looks different from all of the other spots on your skin. Another guide to identifying melanoma is the ABCDE rule:

  • Asymmetry. One side, or half, of a mole or birthmark, doesn’t match the other.
  • Border. The edges are irregular, ragged, notched, or blurred.
  • Color. The color isn’t the same all over.
  • Diameter. The spot is larger than the size of a pencil eraser.
  • Evolving. The mole or spot is changing in size, shape, or color.

Skin cancer occurs when errors (mutations) occur in the DNA of skin cells. These mutations cause the cells to grow out of control and form a mass of cancer cells. Much of the damage to DNA in skin cells results from ultraviolet (UV) radiation found in sunlight and in the lights used in tanning beds.

But sun exposure doesn’t explain skin cancers that develop on skin not ordinarily exposed to sunlight. This indicates that other factors may contribute to your risk of skin cancer, such as exposure to toxic substances or having a condition that weakens your immune system.
Factors that may increase your risk of skin cancer include:

  • Fair skin. Having less pigment (melanin) in your skin provides less protection from UV radiation. If you have blond or red hair, light-colored eyes, and you freckle or sunburn easily, you’re more likely to develop skin cancer than is a person with darker skin.
  • History of sunburns. Having had one or more blistering sunburns as a child or teenager increases your risk of developing skin cancer as an adult.
  • Excessive sun exposure. Anyone who spends considerable time in the sun may develop skin cancer, especially if the skin isn’t protected by sunscreen or clothing. Tanning, including exposure to tanning lamps and beds, also puts you at increased risk.
  • Sunny or high-altitude climates. People who live in sunny, warm climates are exposed to more sunlight than are people who live in colder climates. Living at higher elevations, where the sunlight is strongest, also exposes you to more radiation.
  • Moles. People who have many moles or abnormal moles called dysplastic nevi are at increased risk of skin cancer. The abnormal moles — which look irregular and are typically larger than normal moles — are more likely than others to become cancerous in the future.
  • Precancerous skin lesions. Skin lesions known as actinic keratosis can increase your risk of developing skin cancer. They typically appear as rough, scaly patches, and that range in color from brown to dark pink.
  • Family history. If one of your parents or a sibling has had skin cancer, you may have an increased risk of the disease.

After learning you have skin cancer, additional tests may be needed to determine its stage.
Because superficial skin cancers such as basal cell carcinoma rarely spread, a biopsy that removes the entire growth often is the only test needed to determine the cancer stage. If you have a large squamous cell carcinoma or melanoma, your doctor may recommend further tests to determine the extent of cancer.

Doctors use the Roman numerals I through IV to indicate cancer’s stage. Stage I cancers are small and limited to the area where they began. Stage IV indicates advanced cancer that has spread to other areas of the body.

Treatment options vary, depending on the size, type, depth and location of the lesion. Small cancers limited to the surface of the skin may not require treatment beyond an initial biopsy that removes the growth. If additional treatment is needed, options may include:

Freezing. Your doctor may destroy actinic keratoses and some small, early skin cancers by freezing them with liquid nitrogen (cryosurgery). The dead tissue sloughs off when it thaws.

Excisional surgery. This type of treatment may be appropriate for any type of skin cancer. Your doctor cuts out (excises) the cancerous tissue and a surrounding margin of healthy skin.

Radiation therapy. Radiation therapy may be an option when surgery may not completely remove all cancer cells.

Chemotherapy. For cancers limited to the top layer of skin, creams or lotions containing anti-cancer agents may be applied directly to the skin. Oral or intravenous (IV) chemotherapy drugs may be used to treat skin cancers that have spread to other parts of the body.

Photodynamic therapy. This treatment destroys skin cancer cells with a combination of laser light and drugs that makes cancer cells sensitive to light.

Biological therapy. Biological treatments stimulate your immune system to kill cancer cells.
          Excerpt From: The Mayo Clinic. “Mayo Clinic A to Z Health Guide”.