Abstract 2765: Evaluation of family history of cancer in first-degree relatives and increased cancer risk: A multinational study

Abstract

Abstract Family history of cancer is a known risk factor for several of the more prevalent cancer types. However, familial aggregation of cancer may not follow the genetic linkage pattern seen with most inherited cancer syndromes. In these instances, clustering may be due to unknown hereditary genetic mutations or to an aggregation of environmental risk factors and such clustering may still confer a significant risk. We assessed the association between family history of cancer in first-degree relatives and cancer risk among 9,122 cancer cases and 76,537 controls in a multinational study. Analyses also included evaluation of breast, colon and prostate cancer risk associated with family history of these respective cancer types. Cases were verified by physician diagnosis and all study participants were administered an in-depth survey to ascertain various demographic and lifestyle factors as well as a complete family history of cancer among first-degree relatives. Multivariable logistic regression was used to assess the association between family history of cancer and cancer risk. Among all subjects, the odds ratio (OR) for individuals with a family history of cancer was 1.79 [95% confidence interval = 1.7-1.9] after adjusting for age, gender, BMI, smoking pack years and ethnicity. Additionally, a greater cancer risk was associated with increasing number of first-degree relatives with a history of cancer. Ethnic groups studied included Caucasian-Americans, African-Americans, Hispanic/Latinas and Caucasian-Polish. All ethnic groups showed a significant association between family history of cancer and cancer risk with the highest adjusted OR of 2.65 [95% confidence interval = 2.0-3.6] among the Hispanic/Latina group. Further analyses indicated that family history of colon, breast and prostate cancer was significantly associated with an increased risk of these respective cancer types across studied ethnic groups. In particular, the adjusted ORs for breast, colon and prostate cancer risk in the Caucasian-Polish group were at least double the overall adjusted ORs for each cancer type. Our study shows that family history of cancer is a significant predictor of cancer risk especially among certain ethnic groups. In addition, family history of cancer can represent both a genetic predisposition and/or environmental exposure and risk associated with familial clustering of cancer. Citation Format: Laxmi Modali, Teresa A. Lehman, Ramakrishna Modali, Luke D. Ratnasinghe. Evaluation of family history of cancer in first-degree relatives and increased cancer risk: A multinational study. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2765. doi:10.1158/1538-7445.AM2015-2765