Hemophilus influenzae Infection's Association With Decreased Risk of Breast Cancer

Background: Hemophilus influenzae (H. influenzae) is a common cause of widespread bacterial infections and has been associated with the stabilization of the microbiome. The microbiome, through modulat-ing systemic inflammation with possible upregulation of the NLRP3 inflammasome, may potentiate the development of breast cancer (BC). The purpose of this study was to therefore evaluate the correlation be-tween previous H. influenzae infection and the incidence of BC. Methods: A large national database was used to collect International Classification of Disease Ninth and Tenth Codes to evaluate the inci-dence of BC between January 2010 and December 2019 in patients with and without H. influenzae history. A retrospective cohort study was performed where these groups of individuals were matched by age range, Charlson Comorbidity Index (CCI), and antibiotic treat-ment exposure. Significance and relative risk were obtained using standard statistical procedures. Results: A total of 13,599 patients were matched by age range and CCI in both the experimental and control groups. BC incidence was 259 (1.905%) in the H. influenzae group compared to 686 (5.044%) in the control group (P < 2.2 x 10-16; odds ratio (OR) = 0.604, 95% confidence interval (CI): 0.553 -0.660). Matching by antibiotic treatment exposure resulted in two groups of 3,189 patients, in which BC incidence was 98 (3.073 %) in the H. influenzae group compared to 171 (5.362%) in the control group (P < 2.2 x 10-16; OR = 0.584, 95% CI: 0.515 -0.661). Conclusion: The study shows a statistically significant correlation between H. influenzae and a reduced incidence of BC. These results warrant further research regarding H. influenzae's role in upregulat-ing the NLRP3 inflammasome and its potential role in BC prevention and treatment.