Is there a link between urinary microbiota and bladder cancer?

Excerpt

Bladder cancers are more diagnosed in men than in women, in whom it may be from two to five times more common [1]. This difference in incidence has long been explained by a higher smoking rate among men compared to women, but the increase in smoking among women has not led, as with lung cancers, to a significant increase in female bladder cancer [1]. In an interesting way, the bladder’s urines have been considered sterile by generations of researchers. Recent works have shown that in fact, most of the urines were not sterile and that it was simply a problem of culture techniques, such as short aerobic cultures and the small amount of urine analyzed (1 µl) that prevented the discovery of a more diverse microbial population. The works performed by molecular biology and then by culture helped to highlight the contrary: most of the urines contained a microbiota, which is different in men and women [2]. Among both are especially found Firmicutes, however among women are also found Actinomycetes, including Mycobacteria, and Bacteroidetes [3]. Moreover, women are much more frequently subjected to urinary tract infections than men [4]. Finally, bladder cancer has been treated for a long time with injections of BCG. It is officially a vaccine to prevent tuberculosis, in the bladder [2], it is a mycobacterium and as such an Actinomycetes. Controversial studies suggested also the same potential for Lactobacillus casei [2]. Lactobacillii are Firmicutes found both in men and women’s urinary microbiota [2]. A microbiota mainly consisting in Actinomycetes can be one of the hypotheses for the lower incidence of bladder cancers in women, given that the Actinomycetes may have a preventive effect just like the BCG which has an effect on the treatment and prevention of bladder cancer relapses. The existence of a urinary microbiota leads us to rethink the prevention and risk factors of bladder cancers. …