Skin cancer is a disease in which skin cells lose the ability to divide and grow normally. Healthy skin cells normally divide in an orderly way to replace dead cells and grow new skin. Abnormal cells can grow out of control and form a mass or 'tumor'. When abnormal cells originate in the skin, the mass is called a skin tumor.
A skin tumor is considered benign if it is limited to a few cell layers and does not invade surrounding tissues or organs. But if the tumor spreads to surrounding tissues it is considered malignant or cancerous.
Cancer cells crowd out and destroy nearby healthy cells forming growths called malignant tumors.
Most skin growths, however, are non-malignant, benign (not harmful) tumors.
- Some forms of skin cancer also metastasize. That is, they spread to other parts of the body and start new tumors.
- Skin cancer that spreads to vital organs like the brain or liver can be life threatening.
The skin, which is the human body's largest organ, has several functions. It prevents the body from losing water and other fluid, stores fat, cools the body when sweat evaporates, and makes vitamin D. The skin also protects the body from infection, light, and injury.
There are three layers of skin:
- Epidermis - the outer layer of skin
- Dermis - the middle layer of the skin; contains nerves, blood vessels, sweat glands, hair follicles, and oil-producing cells that keep the skin from drying out
- Fatty layer - the deep layer of skin
Skin cancer begins in the epidermis, the outer layer of skin. The epidermis has three kinds of cells.
- Squamous cells are cells that progressively flatten and fill with protective keratin (a tough, insoluble protein that makes skin almost completely waterproof) to form the outmost surface of the skin.
- Basal cells are small cells located at the base of the epidermis that serve as a reservoir for squamous cells shed from the skin.
- Melanocytes are cells that produce a dark material, or pigment, that gives the skin its color.
Each of these cells can suddenly start to divide abnormally and become cancerous. The main types of skin cancer are named after these cells.
Understanding Cancer
The body is made up of different types of cells that normally divide and multiply in an orderly way. These new cells replace older cells. This process of cell birth and renewal occurs constantly in the body.
'Cancer' is the name for a group of diseases in which certain cells in the body have changed in appearance and function. Instead of dividing and growing in a controlled and orderly way, these abnormal cells can grow out of control.
A tumor is considered benign (not cancerous) if it is limited to a few cell layers and does not invade surrounding tissues or organs. But if the tumor spreads - or has the potential to spread - to surrounding tissues or organs, it is considered malignant, or cancerous.
Cancer (malignant growths) occur when:
- Some cells in the body begin to multiply in an uncontrolled manner..
- The body?s natural defenses, such as certain parts of the immune system, cannot stop uncontrolled cell division.
- These abnormal cells become greater and greater in number.
Facts about skin cancer
- About 1.3 million Americans are diagnosed with skin cancer each year.
- There are three kinds of skin cancer. The rarest, melanoma, is the most serious.
- Almost half of all Americans will have some type of skin cancer at least once by the time they reach age 65.
- Most cases of skin cancer occur in people age 50 and over.
- Childhood sun exposure may decide an individual's risk of skin cancer.
- People with certain skin types have the highest risk of skin cancer.
- Some individuals may inherit a defective gene that increases the risk of malignant melanoma.
- The risk of skin cancer may be rising because of damage to Earth's protective ozone layer..
- A routine skin self-examination is important in early detection of skin cancer.
- The cure rate for skin cancer would be almost 100 percent if all were detected early and treated.
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