Handbook of Tumor Syndromes

Tumors/cancers are characterized by uncontrolled growths of abnormal cells that extend beyond their usual boundaries and disrupt the normal functions of affected organs and systems. While about 75%–80% of tumors/cancers arise sporadically without a family connection, 20%–25% appear to be familial (including 10%–15% nonhereditary familial tumors [or familial tumors] and 5%–10% hereditary familial tumors [or hereditary tumors]). As nonhereditary and hereditary familial tumors often show both tumor