Journal of Turkish Society For Rheumatology, vol.16, no.1, pp.32-37, 2024 (Scopus)
Objective: Autoimmune diseases (ADs) are observed more frequently in patients with breast cancer (BC) compared to healthy population. However, the frequency of ADs in their relatives has not been studied. In the present study, we aimed to compare the frequency of ADs among the first-degree and other relatives of patients with BC with healthy controls. Methods: We included 100 women aged 18 years and older who were followed up with the diagnosis of BC in our oncology clinic, and randomly selected female employees aged 18 and over in our hospital as the control group. The frequencies of ADs among relatives of the two groups were investigated using a detailed questionnaire. Results: Frequency of having at least one relative with AD was 76% in the BC group and 36% in the control group (p<0.001). The frequency of ADs in the relatives of the BC group was 5.5 times higher than in the relatives of the control group. In detailed analyzes, when the degree of kinship was considered, it was found that the risk increased to 11.5 times in the first-degree relatives of BC patients; however, no increased risk was found among more distant relatives. Conclusion: In our study, we found more ADs among the first-degree relatives of patients with BC compared to the control group. This result suggests that common genetic factors may be playing roles in the pathogenesis of BC and ADs.