Abstract P2-11-17: Feasibility of microbiome analysis from random periareolar fine needle aspiration in premenopausal women at increased risk for breast cancer
Authors: Nye Lauren E , Klemp Jennifer R , Powers Kandy R , O'Dea Anne P , Kreutzjans Amy L , Metheny Trina , Phillips Teresa A , Carlson Susan E , Kimler Bruce F , Fabian Carol J 
Published: March 2022

Abstract
Background: Nearly 10% of breast cancers (BC) are diagnosed in premenopausal woman under age 45 and of childbearing potential. Women considering future childbearing are typically excluded from BC prevention trials and are ineligible for standard of care chemoprevention. More biomarkers are needed to support BC prevention trials in this young cohort. Women of childbearing potential are encouraged to supplement diet with minimum of 300mg of EPA + DHA omega-3 fatty acids (FA) per day. EPA and DHA are thought to have a favorable effect on the gut microbiome implicated in cancer development. Few studies have characterized the breast microbiome by core biopsy or surgical sample but to our knowledge no studies have explored the feasibility of breast microbiome collection using the less invasive technique Random Periareolar Fine Needle Aspiration (RPFNA). In a pilot study, we demonstrated feasibility of recruiting premenopausal women considering future pregnancy to a BC prevention trial with a 6-month intervention of omega-3 FA supplementation (19-A-1921-SABCS). RPFNA was used to collect breast tissue for biomarker analysis, which is a mildly invasive technique used for repeated sample collection in BC prevention trials. Objectives: 1) To determine the feasibility of characterizing breast microbiome from specimens collected by RPFNA in premenopausal woman at high risk for BC, 2) To identify changes in the breast and stool microbiome with omega-3 FA supplementation in this population. Methods: Ten women between the ages of 21 and 40 who were considering future pregnancy and at high risk for BC were enrolled to a pilot study and took Omega-3-Acid Ethyl Ester (total of 750mg DHA and 930mg EPA) daily for 6 months. Tissue collection with RPFNA of breast as well as blood, urine and stool were completed at baseline and off-study visit. RPFNA samples from the first 2 passes at each site of breast (4 sites total) were collected for microbiome and placed in a 2mL tube with 0.5 – 1cc of PBS and flash frozen and stored at -80C. DNA was isolated from RPFNA samples using QIAamp DNA Mini Kit (51304). Microbiome profiling analysis was performed by Veracet using 16S V4 rRNA gene sequencing on the Illumina MiSeq platform. Wilcoxon signed rank test was used to compare paired samples. Results: Of the 10 women enrolled, median age was 33 years (range 22-37). 90% (9 of 10) returned for off-study visit. Of the 9 women who completed the off-study visit, 2 elected to not undergo off-study RPFNA. There were 16 total stool samples and 17 total RPFNA samples for microbiome evaluation. There were 6 paired (baseline and off-study) stool and 7 paired RPFNA samples. Mean DNA concentration from RPFNA samples was 10.36ng/µl (range 0.62 – 74.10). From all samples, 52.1% of operational taxonomic units (OTUs) were classified at the genus level. Breast samples were sequenced to a depth of mean 27,767 reads (range 5,745 – 125,445) and stool to a depth of mean 119,296 reads (range 72,979 – 188,867). The alpha diversity metric of OTU richness was 1069 (breast) and 438 (stool). Shannon diversity was 4.51 (breast) and 3.89 (stool). Mean OTU richness for baseline and off-study RPFNA samples were 1098 and 1028 respectively (V = 25, p value = 0.076). Mean OTU richness for baseline and off-study stool samples were 440 and 437 respectively (V = 15, p value = 0.40). Conclusion: We demonstrated feasibility of analyzing breast microbiome from an RPFNA specimen. Additional investigation with modifications to technique and/or sample population is. needed to achieve adequate sequencing depth for characterization of breast microbiome. Lower depth of sequencing in breast samples is thought to reflect differences in microbial DNA quantity. We were unable to assess change in microbiome composition in breast or stool samples with omega-3 fatty acid supplementation due to small sample size.
Citation Format: Lauren E Nye, Jennifer R Klemp, Kandy R Powers, Anne P O'Dea, Amy L Kreutzjans, Trina Metheny, Teresa A Phillips, Susan E Carlson, Bruce F Kimler, Carol J Fabian. Feasibility of microbiome analysis from random periareolar fine needle aspiration in premenopausal women at increased risk for breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P2-11-17.