Family History and Risk of Breast Cancer: Results of Tabari Cohort Study

AimIn the present study, we aimed to investigate the association of positive cancer family history, including breast and other kinds of cancers in both first- and second-degree relatives with risk of breast cancer in a large-scale population-based cohort study.MethodIn the present case-control study, data collected in the enrollment phase of the Tabari cohort study (TCS) were utilized. The case group consists of all participants with breast cancer (51 individuals) in TCS. Subjects in control groups (twice of case group) were matched by age and selected randomly from the study population. Family history of cancer in participants with and without breast cancer was compared using chi-squared. Univariate and multivariable logistic regression was utilized to adjust confounding factors.ResultsThe crude and adjusted odds of having breast cancer in subjects with a positive family history of breast cancer in the first-degree relatives were 4.47 (95% CI 1.23-16.21) and 10.26 (95% CI 2.13-49.44), respectively. Moreover, the crude and adjusted odds of having breast cancer in subjects with a positive family history of breast cancer in the second-degree relatives were 3.41 (95% CI 1.10-10.51) and 3.87 (95% CI 0.98-15.26), respectively.ConclusionThe finding of the present study demonstrated that a breast cancer family history in first- and second-degree relatives increases the risk of breast cancer; however, there is no association between a family history of other kind of cancer and risk of breast cancer.