A landmark study has identified five types of bacteria associated with aggressive prostate cancer. It is unclear at this stage whether the bacteria is directly causing the cancer but the researchers are confident they can develop new tests to identify aggressive prostate cancer by tracking the presence of these bacteria.
"We already know of some strong associations between infections and cancer,” explained Colin Cooper, lead researcher on the project. “For example, the presence of Helicobacter pylori bacteria in the digestive tract can lead to stomach ulcers and is associated with stomach cancer, and some types of the HPV virus can cause cervical cancer. We wanted to find out whether bacteria could be linked to the way prostate cancer grows and spreads."
To investigate the relationship between bacteria and prostate cancer the researchers gathered prostate tissue and urine samples from more than 600 men. A variety of methods were deployed to detect bacteria in the samples, from whole genome DNA sequencing to anaerobic culture and fluorescent microscopy.
Five types of bacteria were ultimately found to be associated with the most aggressive forms of prostate cancer, three of those were entirely new species. The presence of one or more of these bacteria could be linked with more rapid progression of disease.
Rachel Hurst, first author on the new study, stressed it is still early days for the research and the findings raise plenty of novel questions. Even if the link between these bacteria and prostate cancer is verified in future studies it isn’t yet understood if the relationship is causal.
"We also identified potential biological mechanisms of how these bacteria may be linked to cancer,” noted Hurst. "Among the things we don't yet know is how people pick up these bacteria, whether they are causing the cancer, or whether a poor immune response permits the growth of the bacteria.”
Perhaps the most immediate outcome from the findings could be a potential diagnostic test to help doctors and patients identify aggressive prostate cancer before it develops. Co-author Daniel Brewer said it is possible to produce a quick and easy test to detect these bacteria that could better guide treatment decisions.
"Knowing when we can watch and wait or whether we need to start treatment is a major challenge for people with prostate cancer,” said Brewer. “If we can target aggressive cancers while sparing others from unnecessary treatment it will dramatically improve the way we manage this disease.”
Beyond a new diagnostic test the most exciting prospect coming out of this study is the possibility these bacteria directly play a role in causing prostate cancer. The researchers suggest it is likely the microbes play some kind of role in either triggering the development of cancer or speeding up tumor growth.
A number of hypotheses are raised to explain how the bacteria could be causing prostate cancer but it’s all incredibly speculative at this point. Now that a clear association has been reported the real work to explore potential causal mechanisms can begin.
Hayley Luxton, from Prostate Cancer UK, said the implications of finding a bacterial cause for prostate cancer would be enormous. Speaking to The Guardian, Luxton said the research could “revolutionize” prostate cancer treatment.
“If the team can demonstrate that these newly identified bacteria can not only predict, but actually cause aggressive prostate cancer, for the first time we may actually be able to prevent prostate cancer occurring,” said Luxton. “This would be a huge breakthrough that could save thousands of lives each year.”
The new study was published in the journal European Urology Oncology.
Source: University of East Anglia