An example is given for breast cancer. The three major classifications of normal body tissue are epithelial, connective and muscle, and nerve tissue. Epithelial tissues cover all external body surfaces and line all internal spaces and cavities. The skin, mucous membranes, gastrointestinal tract, and the lining of the bladder are examples of epithelial tissues. The functions of epithelial tissues are to protect, excrete, and absorb.
Cancer originating in the epithelial tissue is called a carcinoma.
Connective tissue consists of elastic, fibrous, and collagenous tissues, such as bone, cartilage, and fat. The function of such tissue is to connect, support, and protect. Cancers originating in connective tissue and in muscle are called sarcomas. Nerve tissue includes the brain, spinal cord, and nerves. Tumors arising in nerve tissue do not have a common name, but are named specifically for the type of cell involved.