AP BIOLOGY

Detailed explanation-1: -Cancerous tumors spread into, or invade, nearby tissues and can travel to distant places in the body to form new tumors (a process called metastasis). Cancerous tumors may also be called malignant tumors. Many cancers form solid tumors, but cancers of the blood, such as leukemias, generally do not.

Detailed explanation-2: -A number of biochemical and molecular genetic mechanisms are known that enable malignant cells to invade surrounding tissues and gain the ability to spread far beyond the primary tumor site, giving rise to the development of secondary metastatic foci in distant organs and tissues.

Detailed explanation-3: -Metastasis, from the Greek methistanai, meaning to move to another place, describes the ability of cancer cells to penetrate into lymphatic and blood vessels, circulate through these systems and invade normal tissues elsewhere in the body.

Detailed explanation-4: -A malignant tumor, however, is capable of both invading surrounding normal tissue and spreading throughout the body via the circulatory or lymphatic systems (metastasis). Only malignant tumors are properly referred to as cancers, and it is their ability to invade and metastasize that makes cancer so dangerous.

Detailed explanation-5: -The loss of cell-cell adhesion capacity allows malignant tumor cells to dissociate from the primary tumor mass and changes in cell-matrix interaction enable the cells to invade the surrounding stroma; the process of invasion.