Source:http://linkedlifedata.com/resource/umls/id/C1516196
NCI: A group of blood relatives of whom several have had cancer; the mode of aggregation may be genetic and homogeneous, as in familial polyposis of the colon; diverse as in neurofibromatosis; or due to common exposure to a carcinogenic or oncogenic agent, such as a virus. (On-line Medical Dictionary)