Prostate Cancer Research Link as Scientists Discover 18 New Bacterial Species
Researchers at UEA identified 18 new bacterial species in prostate cancer sequencing data, opening new avenues for studying disease progression.
Scientists at the University of East Anglia (UEA) have discovered the genetic blueprints of 18 new bacterial species collected from prostate cancer patients. Most originated from the mouth, including new types of Porphyromonas, which the team previously linked to more aggressive prostate cancer, and Treponema.
Whether these microbes contribute to prostate cancer is unknown, but the work provides fresh insights into microorganisms in cancer patients and could uncover links that improve understanding of how the disease develops. Crucially, the discovery shows how detailed bacterial genomes can be assembled from sequencing data left over when researchers study human DNA, at no additional cost and without collecting an extra sample.
Unlocking discarded genetic data
When a tumour or blood sample is sequenced, a small proportion of reads do not match human DNA and are normally filtered out as noise and discarded. In this study, the UEA team kept these reads and applied metagenomic assembly to rebuild whole bacterial genomes from the fragments, screening 2,176 sequencing datasets.
The team recovered 249 near-complete bacterial genomes from 194 prostate cancer patients. 24 of these did not match any species on record. Porphyromonas, the genus that includes the principal bacterium behind gum disease, was the most frequently recovered. The team has given formal provisional names to 16 of the new organisms, including Candidatus Porphyromonas leptis, Candidatus Treponema oralis and Candidatus Nanosyncoccus prostatocharitus.
Dr Abraham Gihawi, of UEA’s Norwich Medical School and first author of the study, said: “Now that we have the genomes of these bacteria, we can develop tests for them in clinical samples, work out how we can grow them and begin to study their genes and how they might be linked with cancer.”
“Every one of these organisms was hiding in plain sight. The data had already been generated, paid for and analysed for a completely different purpose, and the bacterial sequences were sitting in the part everyone throws away.”
“The question was whether anything useful would survive that process, and the answer turned out to be yes. One of the newly identified species proved to be almost an exact genetic match to a previously documented bacterium, suggesting that the discovery is real and not an error in the data.”
“There is an enormous volume of cancer sequencing data in archives around the world, and we can use these to look for evidence of new bacteria.”
The oral connection to prostate health
The role of oral bacteria in diseases elsewhere in the body is well established. For instance, Viridans streptococci, which are common in the mouth, cause around 1 in 5 cases of the heart condition infective endocarditis. Similarly, Fusobacterium nucleatum can spread with bowel tumours to the liver, where antibiotics have been shown to reduce both the bacterium and tumour growth in laboratory models.
Evidence is also emerging that men with gum disease have a slightly higher risk of developing prostate cancer. Porphyromonas gingivalis, the main bacterium behind gum disease, has been found in both dental plaque and prostate fluid from the same patients. Furthermore, in 2024, researchers reported that Porphyromonas gingivalis may worsen benign prostate enlargement through an inflammatory mechanism described as an oral-prostate axis.
Progress in studying these microbes has been hampered because many have never been grown in the laboratory, lack reference genomes and cannot be detected with species-specific tests. This study addresses that gap by predicting growth conditions and developing a validated DNA test to detect one species with precision.
Professor Daniel Brewer, of UEA’s Norwich and senior author, said: “The bacteria we recovered are overwhelmingly oral organisms. Part of that is simply that there are far more bacteria in the mouth than in prostate tissue, so they assemble more readily. But the mouth keeps turning up in prostate cancer research, and these are the organisms at the centre of it.”
“We reported in 2022 that men carrying a set of anaerobic bacteria, several of them from the oral cavity, were more than twice as likely to see their cancer progress. In bowel cancer, that kind of observation has already been followed through to the point where an oral bacterium is treated as a target. Prostate cancer is some way behind, and the reason is practical rather than scientific: the organisms involved had never been properly characterised.”
“A biomarker is only useful if you can measure it, and you cannot measure an organism that has no genome and no test.”
“Until now we could say a type of bacteria was involved, which lumps very different species together. We can now work species by species, asking whether one of them is driving aggressive disease and whether doing anything about it changes the outcome.”
Global collaboration and future outlook
The study is part of the Pan Prostate Cancer Group (PPCG), an international consortium co-founded and co-led by scientists at UEA and The Institute of Cancer Research, London. The collaboration brings together whole-genome sequencing and molecular data from more than 2,000 prostate cancers across nine countries to map the disease and improve patient management.
In the UK, the work was co-funded by Prostate Cancer UK and Cancer Research UK, alongside funding from a range of national and international organisations supporting participating research groups worldwide.
Professor Ros Eeles, co-founder of the PPCG and consultant at The Royal Marsden NHS Foundation Trust, said: “We know that prostate cancer is not one single disease. There are a range of ways that prostate cancer develops and behaves, and we need to understand the biology behind those differences in order to detect and treat the cancer correctly.”
“The international team we have created has brought together an enormous amount of molecular information from more than 2,000 tumours worldwide. With these data, we have already uncovered clues that could help identify which prostate cancers are most likely to become aggressive. Today, this consortium publication has revealed an entirely new avenue for research, identifying bacteria associated with prostate cancer that could, in the future, be used to detect or treat cancer.”
“Our long-term goal is to help ensure that patients receive the right treatment at the right time, based on the biology of their individual cancer rather than a one-size-fits-all approach.”
Professor Cooper, professor of cancer genetics at UEA’s Norwich, added: “This group was built to answer why two men with the same diagnosis can have such different outcomes. Most of our answers so far have come from the tumour’s own genetics, which tell us a great deal but which we cannot change.”
“Bacteria are different. If an organism contributes to aggressive prostate cancer, that is something that could potentially be treated or prevented. Very little else in this disease offers that.”
“We are not claiming these bacteria cause prostate cancer. We have found them, named them and built the tools to study them, which is the step that has to come before anyone can answer the causal question properly. What strikes me is that it cost nothing to do. The data existed, the organisms were in it, and nobody had looked.”
Dr Hayley Luxton, Head of Research Impact at Prostate Cancer UK, said: “We still don’t know for certain if bacteria can cause prostate cancer. Building on previous research Prostate Cancer UK funded that linked specific bacteria with aggressive prostate cancer, this new analytical approach from UEA has not only found bacterial DNA hidden in plain sight within the whole genome of prostate cancer patients but will also help researchers investigate whether these bacteria contribute to aggressive prostate cancer. This is hugely exciting, as it could deepen our understanding of the disease and lead to more targeted and effective treatments for men.”
“The next steps will be to isolate these bacterial strains from patient samples so their relationship to aggressive prostate cancer can be studied more closely. Prostate Cancer UK is dedicated to funding innovative research, and we’re proud to have funded vital research like this to get men the treatments they need. We look forward to seeing what future discoveries will emerge from the PPCG.”
The research was conducted with the PPCG and colleagues at The Institute of Cancer Research, London, the University of Copenhagen, the University of Melbourne, the Wellcome Sanger Institute, Weill Cornell Medicine, the Ontario Institute for Cancer Research and institutions across nine countries.
The paper, titled “Recovering anaerobic bacterial genomes in saliva, tumour and blood whole-genome sequencing data from patients with prostate cancer”, is published in npj Biofilms and Microbiomes.