Potential Role of Vaginal Microbiota in Ovarian Cancer Carcinogenesis, Progression and Treatment

Microbiota transplantation and administration of live biotherapeutic products for the treatment of dysbiosis-associated diseases

INTRODUCTION

The microbiota composition in humans varies according to the anatomical site and is crucial for maintaining homeostasis and an overall healthy state. Several gastrointestinal, vaginal, respiratory, and skin diseases are associated with dysbiosis. Alternative therapies such as microbiota transplantation can help restore microbiota normal composition and can be implemented to treat clinically relevant diseases.

AREAS COVERED

Current microbiota transplantation therapies conducted in clinical trials were included in this review (after searching on MEDLINE database from years 2017 to 2025) such as fecal microbiota transplantation (FMT) against recurrent Clostridioides difficile infection (rCDI) and vaginal microbiota transplantation (VMT) against bacterial vaginosis. Washed microbiota transplantation (WMT) and live biotherapeutic products (LBPs) were also reviewed.

EXPERT OPINION

In microbiota-based transplantation therapy, selecting optimal donors is a limitation. A stool or a vaginal microbiota bank should be implemented to overcome the time-consuming and expensive process of donor recruitment. Microbiota-based LBPs are also promising treatment alternatives for rCDI and other dysbiosis-associated diseases. Specific LBPs could be engineered out of donor fluids-derived strains to achieve the selection of specific beneficial microorganisms for the treatment of specific dysbiosis-associated diseases. Personalized microbiota-based treatments are promising solutions for dysbiosis-associated diseases, which remains an important necessity in clinical practice.

Small Biological Fighters Against Cancer: Viruses, Bacteria, Archaea, Fungi, Protozoa, and Microalgae

Despite the progress made in oncological theranostics, cancer remains a global health problem and a leading cause of death worldwide. Multidrug and radiation therapy resistance is an important challenge in cancer treatment. To overcome this great concern in clinical practice, conventional therapies are more and more used in combination with modern approaches to improve the quality of patients' lives. In this review, we emphasize how small biological entities, such as viruses, bacteria, archaea, fungi, protozoans, and microalgae, as well as their related structural compounds and toxins/metabolites/bioactive molecules, can prevent and suppress cancer or regulate malignant initiation, progression, metastasis, and responses to different therapies. All these small biological fighters are free-living or parasitic in nature and, furthermore, viruses, bacteria, archaea, fungi, and protozoans are components of human and animal microbiomes. Recently, polymorphic microbiomes have been recognized as a new emerging hallmark of cancer. Fortunately, there is no limit to the development of novel approaches in cancer biomedicine. Thus, viral vector-based cancer therapies based on genetically engineered viruses, bacteriotherapy, mycotherapy based on anti-cancer fungal bioactive compounds, use of protozoan parasite-derived proteins, nanoarchaeosomes, and microalgae-based microrobots have been more and more used in oncology, promoting biomimetic approaches and biology-inspired strategies to maximize cancer diagnostic and therapy efficiency, leading to an improved patients' quality of life.

Microbiota transplantation

Microbiota refers to a collection of living microorganisms, including bacteria, yeasts, and viruses, that coexist in various sites of the human body. Microbiota can perform multiple functions in the body, which have an essential effect on human health and homeostasis. For example, the microbiota can digest polysaccharides, produce vitamins, modulate the immune system, and protect the body against pathogens. Various factors can occasionally alter the microbiota population in the human body, a condition known as dysbiosis. Dysbiosis can disrupt the homeostasis of a person's body and cause disease. Recent years have witnessed efforts to restore the microbiota population of an individual's body to its original state and eradicate dysbiosis through microbiota transplantation. The noteworthy point is that different methods such as fecal microbiota transplantation, vaginal microbiota transplantation (VMT), skin microbiota transplantation (SMT), oral microbiota transplantation (OMT), washed microbiota transplantation (WMT), and sinonasal microbiota transplantation (SiMT) are used for microbiota transplantation (MT). According to the results of studies and the usefulness of MT in improving a person's health, the purpose of this study is to investigate different methods of MT to eliminate dysbiosis.

Altered microbial diversity and composition of multiple mucosal organs in cervical cancer patients

OBJECTIVES

The aim of this study was to characterize the microbiome of multiple mucosal organs in cervical cancer (CC) patients.

METHODS

We collected oral, gut, urinary tract, and vaginal samples from enrolled study participants, as well as tumor tissue from CC patients. The microbiota of different mucosal organs was identified by 16S rDNA sequencing and correlated with clinical-pathological characteristics of cervical cancer cases.

RESULTS

Compared with controls, CC patients had reduced α-diversity of oral and gut microbiota (pOral_Sob < 0.001, pOral_Shannon = 0.049, pOral_Simpson = 0.013 pFecal_Sob = 0.030), although there was an opposite trend in the vaginal microbiota (pVaginal_Pielou = 0.028, pVaginal_Simpson = 0.006). There were also significant differences in the β-diversity of the microbiota at each site between cases and controls (pOral = 0.002, pFecal = 0.037, pUrine = 0.001, pVaginal = 0.001). The uniformity of urine microbiota was lower in patients with cervical squamous cell carcinoma (pUrine = 0.036) and lymph node metastasis (pUrine_Sob = 0.027, pUrine_Pielou = 0.028, pUrine_Simpson = 0.021, pUrine_Shannon = 0.047). The composition of bacteria in urine also varied among patients with different ages (p = 0.002), tumor stages (p = 0.001) and lymph node metastasis (p = 0.002). In CC cases, Pseudomonas were significantly enriched in the oral, gut, and urinary tract samples. In addition, Gardnerella, Anaerococcus, and Prevotella were biomarkers of urinary tract microbiota; Abiotrophia and Lautropia were obviously enriched in the oral microbiota. The microbiota of tumor tissue correlated with other mucosal organs (except the gut), with a shift in the microflora between mucosal organs and tumors.

CONCLUSIONS

Our study not only revealed differences in the composition and diversity of the vaginal and gut microflora between CC cases and controls, but also showed dysbiosis of the oral cavity and urethra in cervical cancer cases.

Individuality and generality of intratumoral microbiome in the three most prevalent gynecological malignancies: an observational study

Growing evidence have indicated the crucial role of intratumor microbiome in a variety of solid tumor. However, the intratumoral microbiome in gynecological malignancies is largely unknown. In the present study, a total of 90 Han patients, including 30 patients with cancer in cervix, ovary, and endometrium each were enrolled, the composition of intratumoral microbiome was assessed by 16S rDNA amplicon high throughput sequencing. We found that the diversity and metabolic potential of intratumoral microbiome in all three cancer types were very similar. Furthermore, all three cancer types shared a few taxa that collectively take up high relative abundance and positive rate, including Pseudomonas sp., Comamonadaceae gen. sp., Bradyrhizobium sp., Saccharomonospora sp., Cutibacterium acnes, Rubrobacter sp., Dialister micraerophilus, and Escherichia coli. Additionally, Haemophilus parainfluenzae and Paracoccus sp. in cervical cancer, Pelomonas sp. in ovarian cancer, and Enterococcus faecalis in endometrial cancer were identified by LDA to be a representative bacterial strain. In addition, in cervical cancer patients, alpha-fetoprotein (AFP) (correlation coefficient = -0.3714) was negatively correlated (r = 0.4, 95% CI: 0.03 to 0.7) with Rubrobacter sp. and CA199 (correlation coefficient = 0.3955) was positively associated (r = 0.4, 95% CI: 0.03 to 0.7) with Saccharomonospora sp.. In ovarian cancer patients, CA125 (correlation coefficient = -0.4451) was negatively correlated (r = -0.4, 95% CI: -0.7 to -0.09) with Porphyromonas sp.. In endometrial cancer patients, CEA (correlation coefficient = -0.3868) was negatively correlated (r = -0.4, 95% CI: -0.7 to -0.02) with Cutibacterium acnes. This study promoted our understanding of the intratumoral microbiome in gynecological malignancies.IMPORTANCEIn this study, we found the compositional spectrum of tumor microbes among gynecological malignancies were largely similar by sharing a few taxa and differentiated by substantial species owned uniquely. Certain species, mostly unreported, were identified to be associated with clinical characteristics. This study prompted our understanding of gynecological malignancies and offered evidence for tumor microbes affecting tumor biology among cancers in the female reproductive system.

Exploring the Relationship between Ovarian Cancer and Genital Microbiota: A Systematic Review and Meta-Analysis

Ovarian cancer (OC) remains a significant health challenge globally, with high mortality rates despite advancements in treatment. Emerging research suggests a potential link between OC development and genital dysbiosis, implicating alterations in the microbiome composition as a contributing factor. To investigate this correlation, a meta-analysis was conducted following PRISMA and MOOSE guidelines, involving eight studies encompassing 3504 patients. Studies investigating the role of upper and inferior genital tract dysbiosis were included, with particular reference to HPV infection and/or history of pelvic inflammatory disease. The analysis revealed no significant difference in genital dysbiosis prevalence between OC patients and healthy controls. Although previous literature suggests associations between dysbiosis and gynecologic cancers, such as cervical and endometrial cancers, the findings regarding OC are inconclusive. Methodological variations and environmental factors may contribute to these discrepancies, underscoring the need for standardized methodologies and larger-scale studies. Despite the limitations, understanding the microbiome's role in OC development holds promise for informing preventive and therapeutic strategies. A holistic approach to patient care, incorporating microbiome monitoring and personalized interventions, may offer insights into mitigating OC risk and improving treatment outcomes. Further research with robust methodologies is warranted to elucidate the complex interplay between dysbiosis and OC, potentially paving the way for novel preventive and therapeutic approaches.

Racial Differences in Vaginal Fluid Metabolites and Association with Systemic Inflammation Markers among Ovarian Cancer Patients: A Pilot Study

The vaginal microbiome differs by race and contributes to inflammation by directly producing or consuming metabolites or by indirectly inducing host immune response, but its potential contributions to ovarian cancer (OC) disparities remain unclear. In this exploratory cross-sectional study, we examine whether vaginal fluid metabolites differ by race among patients with OC, if they are associated with systemic inflammation, and if such associations differ by race. Study participants were recruited from the Ovarian Cancer Epidemiology, Healthcare Access, and Disparities Study between March 2021 and September 2022. Our study included 36 study participants with ovarian cancer who provided biospecimens; 20 randomly selected White patients and all 16 eligible Black patients, aged 50-70 years. Acylcarnitines (n = 45 species), sphingomyelins (n = 34), and ceramides (n = 21) were assayed on cervicovaginal fluid, while four cytokines (IL-1β, IL-10, TNF-α, and IL-6) were assayed on saliva. Seven metabolites showed >2-fold differences, two showed significant differences using the Wilcoxon rank-sum test (p < 0.05; False Discovery Rate > 0.05), and 30 metabolites had coefficients > ±0.1 in a Penalized Discriminant Analysis that achieved two distinct clusters by race. Arachidonoylcarnitine, the carnitine adduct of arachidonic acid, appeared to be consistently different by race. Thirty-eight vaginal fluid metabolites were significantly correlated with systemic inflammation biomarkers, irrespective of race. These findings suggest that vaginal fluid metabolites may differ by race, are linked with systemic inflammation, and hint at a potential role for mitochondrial dysfunction and sphingolipid metabolism in OC disparities. Larger studies are needed to verify these findings and further establish specific biological mechanisms that may link the vaginal microbiome with OC racial disparities.

Gynecological Cancers and Microbiota Dynamics: Insights into Pathogenesis and Therapy

In recent years, the relationship between the microbiota and various aspects of health has become a focal point of scientific investigation. Although the most studied microbiota concern the gastrointestinal tract, recently, the interest has also been extended to other body districts. Female genital tract dysbiosis and its possible impact on pathologies such as endometriosis, polycystic ovary syndrome (PCOS), pelvic inflammatory disease (PID), and gynecological cancers have been unveiled. The incursion of pathogenic microbes alters the ecological equilibrium of the vagina, triggering inflammation and compromising immune defense, potentially fostering an environment conducive to cancer development. The most common types of gynecological cancer include cervical, endometrial, and ovarian cancer, which occur in women of any age but especially in postmenopausal women. Several studies highlighted that a low presence of lactobacilli at the vaginal level, and consequently, in related areas (such as the endometrium and ovary), correlates with a higher risk of gynecological pathology and likely contributes to increased incidence and worse prognosis of gynecological cancers. The complex interplay between microbial communities and the development, progression, and treatment of gynecologic malignancies is a burgeoning field not yet fully understood. The intricate crosstalk between the gut microbiota and systemic inflammation introduces a new dimension to our understanding of gynecologic cancers. The objective of this review is to focus attention on the association between vaginal microbiota and gynecological malignancies and provide detailed knowledge for future diagnostic and therapeutic strategies.