ABSTRACT
A tumor or neoplasm is an abnormal cellular growth in which regulation of the cell cycle has been lost, and cell proliferation is uncontrolled. Benign tumors are noninvasive. Malignant tumors or cancers are always locally invasive, and usually invade the lymphatic and blood vascular systems. These distribute the neoplastic cells to distant localities, where they set up secondary growths, or metastases.
