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Phoenix, Arizona (UroToday.com) Dr. Steinberg presented in his speech the role of the microbiome in bladder cancer. The microbiome is made up of all the bacteria, viruses and fungi that coexist in our body. There are complex interactions with host cells and the immune system. The microbiome can be altered by dietary and environmental factors.
The metabolic functions of the body can be altered by the microbiome and this can strengthen or suppress the cancer.
According to Dr. Steinberg, the urine is not sterile and sequencing with a 16-second ribosomal RNA amplification shows that the urine is filled with various microorganisms that are not typically grown in standard urine cultures (1). The urine microbiota has many potential roles, including commensal or pathogenic. In addition, in the urine, bacteria produce neurotransmitters capable of interacting and regulating the maintenance of epithelial junctions. Commensal bacteria can produce antimicrobials to kill pathogens and degrade harmful products. They can also prime the epithelial and immune defenses.
The signaling molecules and metabolic products of the microbiota influence many intestinal functions: viscera detection, motility, digestion, permeability secretion, energy recovery, mucosal immunity and barrier effect. In addition, the components of the microbiota could potentially enter the circulation and be transported to various organs, which would affect their functionality. The structural components of bacteria and their metabolites are important forces that can induce the development and maturation of organs, as well as physiological processes in the host. This demonstrates the importance of the microbial ecosystem for maintaining a healthy state of health. This balance between intestinal microbial ecosystems, called eubiosis, is a fundamental concept. On the other hand, when balance no longer exists and bacteria do not coexist in the harmony of our body, a disease called dysbiosis can occur, potentially leading to the development of cancer.
In a study conducted in China, median urine was collected in 31 patients with bladder cancer and compared to 18 controls (2). Sequencing was performed using 16s ribosomal RNA. The hypothesis was that patients with bladder cancer would be enriched with bacteria different from those of the controls. The results showed a difference in bacterial diversity among the risk of bladder cancer but not the grade. Specific bacteria were more common in patients with bladder cancer and other more frequent bacteria in controls. The most common bacteria in patients with bladder cancer include Acinetobacter, Aneurococcus and Sphingobacterium.
A prospective randomized, double-blind study evaluated the role of probiotics and bladder cancer. This study compared prophylactic lactobacilli with placebo. A total of 138 patients with non-invasive high and low grade bladder cancer were randomized. The results demonstrated that lactobacillus was associated with a reduction in recurrence (p = 0.01).
Another nested case-control study evaluating 15 malignancies in a large population, the EMR database showed that the risk of bladder cancer was significantly increased with specific antibiotics (3). The authors concluded that recurrent exposure to antibiotics may be associated with an increased risk of cancer. The work presented by the University of Chicago suggests that the types of bacteria present in the urine of patients with recurrent bladder cancer are different.
In conclusion, the complex understanding of the microbiome and its interaction with bladder cancer continues to evolve and, to date, the urinary microbiome is little known in these patients. Bacteria can play a crucial role in carcinogenesis and immunotherapy in response. Additional clinical trials are needed to fully understand the role of the microbiota in these patients.
Presented by: Gary D. Steinberg, University of Chicago, Chicago, IL, USA
References:
Whiteside et al. Nature 2015
Wu P et al. Microbiol Avant Cell Infect. 2018
Boursi B et al. Eur J Cancer 2015
Written by: Hanan Goldberg, MD, Urology Oncology Fellow, OUA, University of Toronto, Princess Margaret Cancer Center, @GoldbergHanan, at the 19th Annual Meeting of the Society of Urologic Oncology (OUA), November 28-30, 2018 – Phoenix, Arizona
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