When certain vaginal bacteria “closely monitor” the progression of cervical cancer

Cervical cancer, the third most frequent female cancer in the world (or even the 2nd in women aged between 15 and 44), is caused by the persistence of the famous papillomavirus (HPV), a public enemy actively tracked down during smear tests. Generally a long precancerous phase, with progressive lesions, precedes the appearance of cancer. Researchers have put forward the hypothesis that the vaginal microbiota might play a part in the risk of contamination with HPV, its persistence and the development of lesions.

Fewer lactobacilli

By studying the microbiota of the cervical mucus of 94 women aged from 18 to 52, researchers have demonstrated that it differs depending on the stage of the disease. The more advanced the lesions, the more the bacterial diversity within the cervical flora for each woman increases and the more the domination of the lactobacilli (rod-shaped bacteria) wanes progressively to the advantage of other bacteria. Unlike the intestinal microbiota, the vaginal microbiota is in equilibrium when it shows low diversity and when the lactobacilli are largely predominant (> 70% of the bacterial community in healthy women). So it is completely the opposite in women with cervical cancer: the diversity is at its maximum and the lactobacilli have lost their impact.

Markers for advanced lesions or cancer

Second observation from the team: the vaginal microbiota of women with high grade lesions or even cancer differs more and more from that of healthy women in terms of the range of bacteria present. New bacterial species (Porphyromonas, Fusobacterium, Prevotella and Campylobacter) seem to go hand in hand with the presence of cervical cancer whilst other bacteria (Sneathia) indicate the presence of high grade lesions. Is it the lesions which destabilise the flora or the imbalance of the flora which participates in the development of the lesions? The causality relationship must still be studied in greater depth.