About Skin Cancer

The Skin

The skin is the body's largest organ. It protects against heat, light, injury, and infection. It helps control body temperature. It stores water and fat. The skin also makes vitamin D.

The skin has two main layers:

• Epidermis:The epidermis is the top layer of the skin. It is mostly made of flat cells. These are squamous cells. Under the squamous cells in the deepest part of the epidermis are round cells called basal cells. Cells called melanocytes make the pigment (color) found in skin and are located in the lower part of the epidermis.

• Dermis:The dermis is under the epidermis. It contains blood vessels, lymph vessels, and glands. Some of these glands make sweat, which helps cool the body. Other glands make sebum. Sebum is an oily substance that helps keep the skin from drying out. Sweat and sebum reach the surface of the skin through tiny openings called pores.

Understanding Skin Cancer

Skin cancer begins in cells, the building blocks that make up the skin. Normally, skin cells grow and divide to form new cells. Every day skin cells grow old and die, and new cells take their place.

Sometimes, this orderly process goes wrong. New cells form when the skin does not need them, and old or damaged cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.

Growths or tumors can be benign or malignant:

• Benign growths are not cancer:
  • Benign growths are rarely life-threatening.
  • Generally, benign growths can be removed. They usually do not grow back.
  • Cells from benign growths do not invade the tissues around them.
  • Cells from benign growths do not spread to other parts of the body.
• Malignant growths are cancer:
  • Malignant growths are generally more serious than benign growths. They may be life-threatening. However, the two most common types of skin cancer cause only about one out of every thousand deaths from cancer.
  • Malignant growths often can be removed. But sometimes they grow back.
  • Cells from malignant growths can invade and damage nearby tissues and organs.
  • Cells from some malignant growths can spread to other parts of the body. The spread of cancer is called metastasis.

Types of Skin Cancer

Skin cancers are named for the type of cells that become cancerous.

The two most common types of skin cancer are basal cell cancer and squamous cell cancer. These cancers usually form on the head, face, neck, hands, and arms. These areas are exposed to the sun. But skin cancer can occur anywhere.

• Basal cell skin cancer grows slowly. It usually occurs on areas of the skin that have been in the sun. It is most common on the face. Basal cell cancer rarely spreads to other parts of the body.
• Squamous cell skin cancer also occurs on parts of the skin that have been in the sun. But it also may be in places that are not in the sun. Squamous cell cancer sometimes spreads to lymph nodes and organs inside the body.

If skin cancer spreads from its original place to another part of the body, the new growth has the same kind of abnormal cells and the same name as the primary growth. It is still called skin cancer.