Intestinal Proportion ofBlautiasp. is Associated with Clinical Stage and Histoprognostic Grade in Patients with Early-Stage Breast Cancer

Abstract

Improving knowledge about breast cancer etiology is crucial in order to propose prevention strategies for this pathology. Gut microbiota is involved in numerous physiopathological situations including cancers. Although its potential involvement in breast cancer through the alteration of the enterohepatic circulation of estrogens and/or the metabolism of phytoestrogens has been discussed for some time, it remains to be demonstrated. The present study seeks to strengthen this hypothesis by identifying possible links between the fecal microbiota composition and clinical characteristics in breast cancer patients. Bacterial DNA was extracted from the feces of 31 patients with early-stage breast cancer and amplified by real-time polymerase chain reaction (qPCR), targeting 16S rRNA sequences specific to bacterial groups, and then analyzed in relation to clinical characteristics. The absolute numbers of total bacteria and of three bacterial groups (Firmicutes, Faecalibacterium prausnitzii, and Blautia) differed significantly according to the patient's body mass index. The percentage and the absolute numbers of certain bacterial groups, namely C. coccoides, F. prausnitzii, and Blautia, differed significantly according to the clinical stages and the histoprognostic grades. Our study highlighted that intestinal microbiota composition in these patients differs according to clinical characteristics and BMI. Further studies are required to clarify the link between breast cancer and intestinal microbiota.

Breast Cancer and Its Relationship with the Microbiota

“…The link between intestinal microbiota dysbiosis and breast cancer has been investigated in several case-control studies, and many hypotheses have been suggested, some of which underline the possible decrease in the metabolic ability of the microbiota and a weakness of the immune system [48]. The results of clinical studies on the relationship between gut microbiota and breast cancer are summarized in Table 1.…”

“…Several studies have described a higher ratio of Firmicutes / Bacteroidetes (F/B) in obese versus lean subjects, although with controversial results [58]. Significant differences in the absolute numbers of total bacteria and of three bacterial groups ( Firmicutes , Faecalibacterium prausnitzii , and Blautia ) were observed in feces as a function of the body mass index (BMI) of women with early-stage breast cancer, with lower number of bacteria in overweight and obese patients [48]. The lower number of Firmicutes bacteria observed in overweight subjects contrasted with other clinical studies showing an increased ratio (F/B) with obesity [59], no effect [60], or a decreased ratio [61] in obese patients.…”

“…The lower number of Firmicutes bacteria observed in overweight subjects contrasted with other clinical studies showing an increased ratio (F/B) with obesity [59], no effect [60], or a decreased ratio [61] in obese patients. The relation between these main phyla and BMI remains unclear [48]. …”

“…Firmicutes and Bacteroidetes phyla were also the most numerous bacteria observed in the feces of 31 women with early-stage breast cancer [48]. This study evaluated the relationship between the composition of gut microbiota with the clinic-biological characteristics of BC, describing that the total number of Bacteroidetes , Clostridium coccoides cluster, C. leptum cluster, F. prausnitzii , and Blautia spp.…”

Dynamic relationships among tumor, immune response, and microbiota

“…Along with genetics, envi ronmental factors contribute to breast cancer development, but what these exact environmental fac tors remain unknown. Although results of their analysis were different from ours, some interesting studies may offer support for certain envi ronmental factors being associated with an increased incidence of breast cancer [36,37] . Urbaniak et al demonstrated that breast tissue contains a diverse population of bacteria [38,39] .…”