Cancer

Cancer occurs when abnormal cells grow out of control. Normal cells in the body grow, divide, and die, and as we become older, our cells divide at a decreasing rate. Cancer cells, however, continue to grow and divide unchecked by the body, and they outlive normal cells. Cancers are capable of both invasion, or spreading into adjacent tissue, and metastasis, or traveling and settling into new, noncontiguous parts of the body. Cancer cells commonly form a tumor, or mass of cells, but they may also circulate in the bloodstream. Carcinogenesis describes the transformation of normal cells to neoplastic cells or abnormal cells that grow uncontrollably. Neoplasia is the process by which neoplasms develop from normal tissue. Cancers generally develop from a single neoplastic cell, commonly ...