The study of genetic and clinicopathological characterisation of Turkish bilateral breast cancer patients

Introduction. Although bilateral breast cancers are a rare condition in the general population, the incidence has increased significantly in BRCA1 and BRCA2 gene carrier breast cancer patients. Besides the genetic susceptibility, many risk factors such as age, first breast cancer diagnosis age, lifestyle, and environmental factors may be effective in the development of this type of cancer. This study aimed to determine BRCA1/2 gene carriage in patients with bilateral breast cancer and to find out the risk factors that may lead to contralateral cancer formation. Material and methods. From 2016 to 2018, in Turkey, we grouped 31 women diagnosed with bilateral breast cancer synchronously and metasynchronously. Analysis of BRCA1 and BRCA2 genes of these women evaluated for clinical and pathological tumour characteristics was performed using the NGS technique. Results. No significant difference was found between the metachronous (MBBC) and synchronous (SBBC) groups in terms of clinical and pathological tumour characteristics. MBBC patients’ age at first diagnosis of breast cancer was lower than SBBC. Also, there was a statistically significant relationship between chronic diseases and MBBC cancers (c2 = 11.519; p = 0.001). In our study, disease-related variants were found only in three patients, and two of these variants were identified the first time in the literature. Conclusion. The risk of bilateral breast cancer of BRCA1/2 carriers increases when the first breast cancer is diagnosed at a young age and there is a significant family history of cancer. MBBC is associated with chronic diseases, and large-scale research will contribute to clarifying this relationship