Black women experience higher mortality from endometrial cancer (EC) than White women, according to published data, and potential reasons for this disparity include increased rates of obesity and more lethal histologic/molecular subtypes. Researchers hypothesized that another biological factor related to this racial disparity may include the EC microbiome.

For a study published in Gynecologic Oncology, Gabrielle M. Hawkins, MD, and colleagues examined tumor specimens from postmenopausal Black and White women undergoing hysterectomy for early-stage endometrioid EC. Dr. Hawkins and colleagues characterized the microbiota of the tumors using rRNA sequencing and examined the microbial component of endometrioid ECs in The Cancer Genome Atlas (TCGA) database for comparison.

Weight Also Impacts Microbial Diversity

Investigators examined 95 early-stage ECs, including 23 from Black patients (24%) and 72 from White patients (76%). Median age was 66 for Black women in the EC cohort and 64 for White women; median BMI was 36 for Black women and 35 for White women. Tumor grades were similarly distributed between Black and White women, according to the study results.

Dr. Hawkins and colleagues found that microbial diversity was increased (P<0.001), and that Firmicutes, Cyanobacteria, and OD1 phyla abundance was greater in tumors from Black versus White women (P<0.001). Genus-level abundance of Dietzia and Geobacillus were decreased in tumors from Black women who were obese versus White women who were obese.

An examination of early-stage ECs in TCGA demonstrated that microbial diversity was greater in ECs from Black versus White women. Researchers found five distinct bacteria distributions when they compared ECs from Black women who were obese versus White women who were obese, with greater abundance of Lactobacillus acidophilus in ECs from Black women noted as the most remarkable difference. Likewise, in TCGA, Dietzia and Geobacillus were more frequent in ECs from White women compared to Black women.

Study Limitations & Future Research

The researchers noted that, to their knowledge, this is the first study to assess the microbial composition of ECs, including a direct evaluation of differences according to race. They also acknowledged several limitations of their research, including the possibility of specimen contamination as the result of processing and handling and the small sample size. Dr. Hawkins and colleagues are currently implementing a prospective study to examine the EC microbiome that “controls for the collection and processing of EC specimens in a sterile fashion,” according to the researchers.

“Ultimately, an improved understanding of the contribution of uterine microbial dysbiosis to EC pathogenesis, as well as the alarming disparities for Black women battling this disease, may result in novel targets for treatment and prevention,” Dr. Hawkins and colleagues wrote.