Cancer is a word used to describe a group of diseases. Each has its own name, its own treatment, and its own chances of being cured. Each is different from the others in many ways, but every cancer, whatever its called or whatever part of the body it is located in, is a disease of the body’s cells. The millions of tiny cells that make up the human body are so small that they can be seen only by looking through a microscope. There are different kinds of cells, but they all make new cells by dividing into two. This is how worn-out, old cells are replaced with strong new ones. When a cell changes and doesn’t do the job it should do for the body, it divides into more cells like itself, then these cells keep dividing into more cells. A group of these cells is a tumor. There are two kinds of tumors. A benign tumor is not cancer. The cells of a benign tumor can crowd out healthy cells, but they cannot spread to other parts of the body. A malignant tumor is cancer. Like a benign tumor, it can take over other healthy cells around it, but it can also spread to other parts of the body. To do this, a cell or group of cells from the tumor breaks away and moves, usually though the blood, to other parts of the body. There they divide and start tumors made of malignant cells like the ones that made up the first tumor. When this happens, it is called metastasis. Skin cancer is the most prevalent of all cancers, and it’s increasingly common. About a million Americans will develop skin cancer this year. It is a disease in which cancer cells are found in the outer layers of skin. Skin protects the body against heat, light, infection, and injury. It also stores water, fat, and vitamin D. The skin has two main layers and several kinds of cells. The top layer of skin is called the epidermis. It contains three kinds of cells: flat, scaly cells on the surface called squamous cells, round cells called basal cells, ...
