Microbiota changes: the unseen players in cervical cancer progression

Abstract

Cervical cancer ranks among the most prevalent cancers globally with high-risk human papillomaviruses implicated in nearly 99% of cases. However, hidden players such as changes in the microbiota are now being examined as potential markers in the progression of this disease. Researchers suggest that changes in the vaginal microbiota might correlate with cervical cancer. This review provides a comprehensive look at the microbiota changes linked with the advancement of cervical cancer. It also scrutinizes the databases from past studies on the microbiota during healthy and cancerous stages, drawing connections between prior findings concerning the role of the microbiota in the progression of cervical cancer. Preliminary findings identify Fusobacterium spp., Peptostreptococcus spp., Campylobacter spp., and Haemophilus spp., as potential biomarkers for cervical cancer progression. Alloscardovia spp., Eubacterium spp., and Mycoplasma spp. were identified as potential biomarkers for HPVs (+), while Methylobacterium spp. may be indicative of HPV (-). However, the study's limitations, including potential biases and methodological constraints, underscore the need for further research to validate these findings and delve deeper into the microbiota's role in HPV development. Despite these limitations, the review provides valuable insights into microbiota trends during cervical cancer progression, offering direction for future research. The review summarizes key findings from previous studies on microbiota during healthy and cancerous stages, as well as other conditions such as CIN, SIL, HPV (+), and HPV (-), indicating a promising area for further investigation. The consistent presence of HPV across all reported cervical abnormalities, along with the identification of distinct bacterial genera between cancerous and control samples, suggests a potential link that merits further exploration. In conclusion, a more profound understanding of the microbial landscape could elucidate the pathogenesis of cervical diseases and inform future strategies for diagnosis, prevention, and treatment.

Keywords: biomarkers; cervical cancer; microbiota changes; progression; vaginal microbiota.

Figure 1

Vaginal microorganisms in a healthy vagina versus a dysbiosis stage in the vagina. Source of image: Authors and adapted from Zhou et al. (2021). The figure reveals the transformation that the vaginal microbiota undergoes between healthy and dysbiotic conditions. In a healthy state, the environment is primarily characterized by the presence of Lactobacillus species. On the other hand, in a state of dysbiosis, the environment is largely dominated by a variety of other bacteria, including Prevotella spp., the bacterium now known as Fannyhessea spp. (formerly Atopobium spp.), Streptococcus spp., and other anaerobic bacteria.

Figure 2

Bacterial composition and diversity. (A) The Venn diagram depicts the overlap of common bacterial types identified in CAN and CONTROL groups, based on the 50 most abundant bacteria in each study. (B) Simpson’s index measures genera diversity across various cervical health conditions. Notably, CONTROL samples exhibit lower diversity compared to CAN, CIN, and SIL conditions. The Kruskal-Wallis test yielded a p-value <0.05, signifying significant differences in diversity between CONTROL vs. CAN and CONTROL vs. CIN. (C) A box plot illustrating the prevalence of HPV infection in control samples across the studied papers. (D) Identification of common bacterial types in HPV (−) and HPV (+) groups in each paper, with unique bacteria within each group highlighted in bold.