Contribution of extended family history in assessment of risk for breast and colon cancer

BACKGROUND: Family history is important for identifying candidates for high risk cancer screening and referral for genetic counseling. We sought to determine the percentage of individuals who would be eligible for high risk cancer screening or genetic referral and testing if family history includes an extended (vs limited) family history. METHODS: Family histories were obtained from 626 women at UVMMC associated mammography centers from 2001 to 2002. ACS guidelines were used to determine eligibility for high risk breast or colon cancer screening. Eligibility for referral for genetic counseling for hereditary breast and colon cancer was determined using the Referral Screening Tool and Amsterdam II screening criteria, respectively. All family histories were assessed for eligibility by a limited history (first degree relatives only) and extended history (first and second degree relatives). RESULTS: Four hundred ninety-nine histories were eligible for review. 18/282 (3.6 %) and 62/123 (12 %) individuals met criteria for high risk breast and colon cancer screening, respectively. 13/18 (72 %) in the high risk breast cancer screening group and 12/62 (19 %) in the high risk colon cancer screening group met criteria based upon an extended family history. 9/282 (1.8 %) and 31/123 (6.2 %) individuals met criteria for genetic counseling referral and testing for breast and colon cancer, respectively. 2/9 (22 %) of individuals in the genetic breast cancer screening group and 21/31 (68 %) individuals in the genetic colon cancer screening group met criteria based upon extended family history. CONCLUSIONS: This is one of the first studies to suggest that first degree family history alone is not adequate for identification of candidates for high risk screening and referral for genetic counseling for hereditary breast and colon cancer syndromes. A larger population is needed to further validate this data. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12875-016-0521-0) contains supplementary material, which is available to authorized users.