Abstract OT2-05-02: Characterization of the oral, gut, and breast tissue microbiomes in women with invasive breast cancer, ductal carcinoma in situ (DCIS), or no history of breast cancer

Background: We now know that there is an interplay between our bodies and the bacteria that we carry, both in health and in disease. Inflammatory diseases associated with disruptions in microbial equilibria, such as periodontal disease and ulcerative colitis, as well as chronic antibiotic use, have been associated with increased risk for cancer development. In a previous small pilot study, we observed differences in the oral microbiomes of women with breast cancer and healthy women. This presentation describes an ongoing study in which we aim to validate our previous findings in a larger cohort of women, as well as extend the microbiomes studied to include the gut and local breast tissue microbiota. Trial design and eligibility criteria: Women with invasive breast cancer or with ductal carcinoma in situ (DCIS) who have not received prior therapy for their disease are eligible for enrollment. A cohort of healthy women will also be enrolled. Sample collection kits containing cheek and stool swab materials are distributed to patients in the clinic, and breast tumor tissue is collected at the time of surgery. Specific aims: 1. To characterize and compare oral and gut microbial diversity from women with early stage invasive breast cancer, women with DCIS, and healthy women; and 2. To characterize the microbiota associated with breast tumor tissue and compare this to healthy breast tissue. Methods: DNA from the three sites is isolated, the bacterial 16S rRNA gene is PCR amplified and sequenced, and the bacterial species present are enumerated. Oral, gut, and breast tissue microbial diversity at the genus and species levels will be assessed using the Shannon diversity index. Student9s t-test will be used to compare the mean diversity index values. Evaluation of microbial diversity and clinical variables will be determined using Spearman or Pearson correlations depending on the distribution of the data. We will also compare oral microbial diversity and clinical variables across racial and ethnic groups to determine if differences in the microbiomes may explain disparities in incidence across these groups. Classification and regression trees (CART) will be employed to develop rule sets based on the abundance of oral bacteria that discriminate breast cancer vs. DCIS vs. healthy controls. Present accrual: As of June, 2015, 32 women with early-stage invasive cancer, 8 women with DCIS, and 9 healthy women received sample collection kits. Breast tumor tissue has been collected from 11 invasive breast cancer cases and 2 DCIS cases. Target accrual: For the oral and gut microbiome analyses: 100 women with early-stage invasive breast cancer, 100 women with ductal carcinoma in situ (DCIS), and 100 healthy women with no history of breast cancer. For the breast tissue microbiome analyses: 20 women with invasive breast cancer, 10 patients with DCIS, and 10 reduction mammoplasty cases from healthy women. Citation Format: Campbell M, O9Meara T, Esserman LJ. Characterization of the oral, gut, and breast tissue microbiomes in women with invasive breast cancer, ductal carcinoma in situ (DCIS), or no history of breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr OT2-05-02.