Victoria Frankel

Cervical Cancer and the Vaginal Microbiome

Feb 17, 2020

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Our gut microbiome can impact our health in many ways, often affecting our risk for many digestive and metabolic conditions. It seems that a lot of focus is spent on treating or preventing these diseases – and rightly so – but there are many other microbiomes on our body that play a close role in our health. In the case of cervical cancerthe fourth most common cancer in women, the vaginal and cervical microbiome have a close relationship to women’s reproductive health. Not unlike the gut microbiome, these microbiomes consist of many beneficial and commensal microbes that help stabilize the pH of the vaginal canal and prevent pathogenic bacteria from taking over.

The microbes that thrive in this environment must maintain a similar balance like our gut microbes. Shifting colony size in any population can have serious effects, including incidences of bacterial vaginosis, a condition similar to gut dysbiosis – or a bacterial imbalance within the vagina. Several studies have noted that this disorder can promote many reproductive health problems including pelvic inflammatory disease. Some studies have even suggested that bacterial vaginosis may heighten the impact of the human papillomavirus (HPV) that is closely linked to cervical cancer incidences.

 

HPV – Not Your Typical Virus

The human papillomavirus is a common sexually transmitted infection that often can be resolved by the natural defenses of our immune system. There are over 200 subtypes of HPV, but only a small fraction of these hold carcinogenic potential. Instead, many scientists have deemed less serious HPV infections a common rule that affects 85% of women, often without any long-term effects. Even so, persistent infection from more high-risk HPV can lead to the development of more serious conditions such as dysplasia and cervical cancer.

Although considered highly treatable due to the quantity of preventative testing in women in the U.S., an estimated 4,000 women die from cervical cancer each year. Despite this, scientists are still struggling to determine what may cause one HPV infection to be highly infectious over another. Various risk factors can heighten the risk for more severe HPV infections, including smoking, immunosuppression therapy, and reproductive factors – however, some researchers speculate the vaginal and cervical microbiome may have a larger part to play.

 

Diversity, Diversity, Diversity

Just as Viome discusses the importance of a diverse and balanced gut ecosystem, various studies have found that women facing a difficult cervical cancer journey may suffer from a less diverse vaginal microbiome. For one such microbial family, lactobacilli work to maintain a normal pH within the vaginal canal and may be more important to women’s reproductive health than previously thought. This family helps lower the pH of the vagina, making it more acidic and less hospitable to many harmful bacteria. Without their activity, the pH of the vaginal environment rises. Cervical cancer studies have found that women with a vaginal pH of less than 5.0 had a 10% lower risk of HPV in comparison to women with a pH of greater than 5.0. However, different strains of lactobacilli have been shown to have different roles – many that may impact the natural homeostasis of the vaginal microbiome, including other antimicrobial activities.

The balance and diversity of the vaginal and cervical microbiome is also considered to be closely regulated by hormones. Depending on the hormonal system and balance, the vaginal microbiome may experience shifts in diversity, including less stable times during menstruation. This has led many experts to question the relationship between the vaginal microbiome and the gut microbiome – a link that still has many scratching their heads. In truth, the gut microbiome has been shown to function much like an endocrine and immune organ as well, regulating hormones and many aspects of inflammation. Furthermore, scientists have found that the microbes that populate the vaginal microbiome originally came from the gut ecosystem. In the future, scientists may even find the relationship between these two microbiomes to be more connected than we thought…

 

But It’s More Than Just Microbes

Researchers have yet to completely discover what pushes HPV over the edge from low-risk to high-risk infection. Just like many diseases, it’s complex and usually requires a variety of factors, combined. A compromised immune system might be what impacts one person more than another – for someone else, their smoking habits. In any case, regular testing has proven to help remove cervical cancer cells in 91% of women who test positive.

Currently, there are 3 vaccines that may also protect against the two primary HPV strains responsible for a significant number of cervical cancer cases. Both HPV-16 and HPV-18 vaccines have proven to be safe and effective in preventing HPV infections, though they are found to be most effective in young individuals who haven’t been previously exposed to any HPV infection. Because of this, the risk is still a concern for many adults.

 

Annual Testing May Be the Answer

Focusing, instead, on preventative care for adults has been the most effective means of reducing cervical cancer mortality. The World Health Organization recommends for every woman from aged 30 and regularly afterward (frequency depends on the screening test used). For women living with HIV who are sexually active, screening should be done earlier, as soon as they know their HIV status. But ultimately, early examination can drastically improve cancer prognosis.

This month, take another step further with your health and make sure you schedule your annual exam to support Cervical Cancer Awareness. For both men and women, HPV can have a profound impact on your reproductive health, including the risk of developing genital warts. Although your risk for cervical cancer may be small – only 0.6% of HPV infections become cancerous – annual exams improve your opportunity to rid any potential malignant cells early on. This a great opportunity to keep your reproductive health at the top of your list!

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Cervical Cancer and the Vaginal Microbiome

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