Normal cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they usually die, and new cells take their place.
But sometimes this process goes wrong. New cells form when the body doesn't need them, and old or damaged cells don't die as they should. The buildup of extra cells often forms a mass of tissue called a growth or tumor.
- Benign growths (such as moles):
- Are rarely a threat to life
- Generally can be removed and usually don't grow back
- Don't invade the tissues around them
- Don't spread to other parts of the body
- Malignant growths (such as melanoma, basal cell cancer, or squamous cell cancer):
- May be a threat to life
- Often can be removed but sometimes grow back
- May invade and damage nearby organs and tissues
- May spread to other parts of the body
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