Bladder Cancer and the Microbiome

There are trillions of microorganisms on or inside the human body. Microorganisms or microbes are tiny living things. They can only be seen under a microscope. These microbes include bacteria, fungi, parasites, or viruses. These organisms living on or inside us make up the microbiome.1

Normally, these microbes are not harmful to humans. In fact, the microbiome plays a key role in our health. For example, the microbes found in our gut help break down certain foods and fight diseases.2

The urinary microbiome

For a long time, people wrongly believed that urine was sterile. This is not true. Research has shown that the urine and bladder have a diverse microbiome. Certain bacteria and other microorganisms are present in a healthy bladder. And changes in the urinary microbiome are linked to bladder cancer and other diseases.2-5

Other factors can also change the urinary microbiome. Some of these factors are:3

  • Age
  • Sex
  • Diet and lifestyle
  • Genetics
  • Surgery
  • Antibiotic use
  • Menopause

Studying the urinary microbiome

Research on the urinary microbiome is still in the early stages. The role of the microbiome when it comes to bladder cancer is not clear. However, researchers have found that certain microbes are more or less common when certain diseases are present.2

But it is not clear whether it is the disease that causes the changes in the microbiome or the changes in the microbiome that cause the disease. Also, it is hard to figure out which microbes are present in a healthy or unhealthy bladder.2,3

We know that many factors can change the makeup of the microbiome. How the urine is obtained also affects which microbes are present. This is likely because some methods of urine collection may introduce new microbes into the sample that were not present in the bladder.3

As a result, the findings from different studies do not fully agree. But we can look at results from different studies to find trends. Doing this shows that Lactobacillus, Prevotella, and Streptococcus are some of the most common microbes found in a healthy bladder.3

Urinary microbiome and bladder cancer

Research shows that people with bladder cancer have a higher amount of Streptococcus, Veillonella, and Corynebacterium bacteria. And one 2022 study found that the bacteria Brucellaceae, Acinetobacter, and E. Shigella are commonly present in people with bladder cancer.3

The microbes related to bladder cancer also depend on biological sex. The exact microbes that are different between sexes is not well understood. Different studies have shown slightly different results. But it is clear that microbes that seem to be more common in men with bladder cancer may or may not be common in women with bladder cancer.2,3

By knowing which bacteria are more commonly found in people with bladder cancer, we can use those bacteria to diagnose bladder cancer. Researchers are also trying to figure out if it is possible to change the urinary microbiome on purpose in order to prevent or treat certain diseases.4,5

Urinary microbiome and treatments

A common treatment for non-muscle invasive bladder cancers is BCG (Bacillus Calmette–Guerin). Certain microbes are common in the urinary microbiome of people who respond well to this treatment. It may be possible to create BCG treatments that are designed for each person’s microbiome. This can make the treatment more successful.3,4

A better understanding of the urinary microbiome can lead to new ways of diagnosing and treating bladder cancer.4

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