Bayesian assessment of the prevalence of <i>BRCA</i>-associated breast cancer in Moscow

Rationale:  For many years, breast cancer has been leading in the cancer structure in women, accounting for 21% from the total number of newly diagnosed cases of malignancies in Russia. The literature on the prevalence of the  BRCA -associated breast cancer is heterogeneous, which might be related to the specifics of the frequentist analysis.  Aim:  To assess the prevalence of  BRCA -associated breast cancer and the probability of sporadic breast cancer in women of the Moscow region by Bayesian statistics.  Materials and methods:  The literature search in the E-library.ru database from January 2010 to March 2019 identified 13 original studies and 8 literature reviews with the data on hereditary breast cancer in the territories of the Russian Federation, Republic of Belarus and Ukraine. The assessment of the prevalence of  BRCA  gene mutation based on the Bayesian statistics and the full probability equation for incompatible events was performed on the data obtained in one study based on molecular genetic tests of 3826 female patients with breast cancer living in the Moscow Region, aged from 22 to 90 years (Russian Scientific Center of Roentgenoradiology). This was the most comprehensive study among those performed in Russia, covering almost all age ranges, with detailed description of the study design, diagnostic methods and the mutations spectrum analyzed.   Results:  The prevalence of  BRCA1 -associated breast cancer in Moscow among women is about 0.037%. The general population prevalence of the most frequent mutations of the  BRCA1  gene ( 5382insC, 185delAG, 300T>G, 2080delA, 3819delGTAAA, 4153delA ) in the female population in Moscow is about 0.05%, or about 0.1% from the total population. The probability of sporadic breast cancer in the female population of Moscow without any gene dominant mutations associated with breast cancer is about 1%.  Conclusion:  For the first time, the Bayesian statistics was used to analyze the prevalence of mutations in the  BRCA1/2  genes in Russia. The results obtained are in good agreement with similar data for the Belgorod region and the Siberian region of Russian Federation, and the Grodno region of Belarus.