The study found that cervical cancer may be caused by an imbalance of vaginal bacteria

Almost all cervical cancers are caused by human papillomavirus (HPV), which is sometimes called the "common cold" of sexually transmitted infections because almost everyone with an active sexual life will be infected with it at some point. Fortunately, the immune system defeats most HPV infections, and only a small percentage of people progress to pre-cancer and eventually cancer. But why can some people clear the infection while others cannot?

To answer this question, Dr. Melissa M. Herbst-Kralovetz of the University of Arizona Cancer Center, an associate professor at the Phoenix Medical School at Union University, studied 100 premenopausal women and found a link between vaginal bacteria and cervical cancer. Compared with cervical cancer and precancerous patients, women with no cervical abnormalities had different vaginal bacterial communities. This difference reveals the direct relationship between "good" bacteria and cervical health, and how "bad" bacteria increase the risk of cancer.

The microbial community referred to here is the bacterial community that lives in the human body. Lactic acid bacteria, for example, are related to probiotics in yogurt — but unlike probiotics in yogurt, certain bacteria found in the vaginal environment actively promote its health. Previous research has shown that women with vaginal microbes predominantly composed of gaseous Lactobacillus are more likely to clear HPV infections. Good bacteria can also hold their ground and prevent harmful bacteria from entering — but sometimes they lose this battle.

In cervical cancer and precancerous patients, lactic acid bacteria — a beneficial bacteria — are replaced by a mixture of harmful bacteria. In the study, as the number of lactic acid bacteria decreased, cervical abnormalities became more serious.

On the other hand, a harmful bacterium called Sneathia has been found to be associated with pre-cancer, HPV infection, and cervical cancer. Sneathia are rod-shaped bacteria that can grow into fiber chains. They are associated with a range of other gynecological diseases, including bacterial vaginosis, miscarriage, premature delivery, HPV infection, and cervical cancer.

Dr. Herbst-Kralovetz's research found for the first time that large populations of Sneathia are associated with all stages of the HPV-to-cancer continuum — from the initial HPV infection, through precancerous lesions, to invasive cervical cancer. This is a significant discovery because it positions Sneathia as a potential marker or contributor across the entire disease progression pathway, not just at one isolated stage.

It remains unclear whether Sneathia actively promotes the formation of HPV infections or cancers, or whether its presence is simply a consequence of the disease environment rather than a cause. The current study provides only a snapshot of women at a point in time. In order to establish causality — and determine whether targeting Sneathia could help prevent or slow cervical cancer — future research must be carried out longitudinally over time.