ABSTRACT
Prior to this time, Lynch and colleagues2 had begun looking at families in which there was a preponderance of breast cancer and ovarian cancer. Since that time two major breast-ovarian cancer susceptibility genes have been cloned and sequenced, namely, the BRCA1 and BRCA2 genes for hereditary breast and/or ovarian cancer (HBOC).3,4 In addition, other major cancer susceptibility genes have been cloned and sequenced, including the APC gene for familial adenomatous polyposis (FAP)5 and the MLH1, MSH2, MSH6, PMS1 and PMS2 genes for hereditary non-polyposis colon cancer (HNPCC).6,7 These scientific advances offer new opportunities for members of families with several relatives with various cancers to discover whether or not they carry a genetic mutation and subsequently have an increased risk of developing cancer.
