By SMart Nutrition International
The human body harbours trillions of microorganisms that form what scientists call the microbiome – a complex ecosystem of bacteria, fungi, and other microbes living symbiotically within us. Far from being mere passengers, these microscopic inhabitants play crucial roles in our health, and groundbreaking research is now revealing their profound influence on cancer development, diagnosis, and treatment.
Important microbial signatures, including Bacteroides fragilis and Fusobacterium nucleatum, have been linked to the development and progression of cancer, providing important information on the processes behind carcinogenesis. Latest research provides an overview of the current understanding of the host-microbe immunological axis and discusses emerging therapeutic strategies centered on microbiota modulation to support human health
Recent scientific advances have illuminated how our microbial communities interact with cancer cells, immune responses, metabolism, and environmental factors. This intricate cross-talk between different biological systems represents one of the most exciting frontiers in oncology research, potentially leading to revolutionary diagnostic and therapeutic approaches.
The relationship between microbes and cancer is remarkably complex. Certain microbial species have been implicated in influencing cancer development, progression, metastasis formation, and even how patients respond to treatment. This discovery has shifted our understanding from viewing microbes as simple bystanders to recognising them as active participants in the cancer journey.
The Microbiome-Cancer Connection
Recent scientific advances have illuminated how our microbial communities interact with cancer cells, immune responses, metabolism, and environmental factors. This intricate cross-talk between different biological systems represents one of the most exciting frontiers in oncology research, potentially leading to revolutionary diagnostic and therapeutic approaches.
The relationship between microbes and cancer is remarkably complex. Certain microbial species have been implicated in influencing cancer development, progression, metastasis formation, and even how patients respond to treatment. This discovery has shifted our understanding from viewing microbes as simple bystanders to recognising them as active participants in the cancer journey.
Saliva: A Window into Cancer Detection
One particularly promising area of research involves using salivary microbiota as a non-invasive diagnostic tool. Unlike traditional methods that often require invasive biopsies, saliva samples can be easily collected and analysed to detect cancer-specific microbial signatures.
Oral Cancer Detection
For patients with oral squamous cell carcinoma, researchers have identified a specific combination of bacterial species – Capnocytophaga gingivalis, Prevotella melaninogenica, and Streptococcus mitis – that serves as a diagnostic indicator with 80% sensitivity and 83% specificity compared to healthy individuals. Intriguingly, whilst these bacteria are normally harmless commensals living in our mouths, they become significantly elevated in cancer patients.
Pancreatic Cancer: A Hidden Enemy Revealed
Perhaps even more remarkable is the potential for saliva testing to detect pancreatic cancer, traditionally one of the most challenging cancers to diagnose early. The combination of Neisseria elongata and S. mitis in saliva samples achieved an impressive 96% sensitivity and 82% specificity in distinguishing pancreatic cancer patients from healthy controls. Additionally, the pairing of Granulicatella adiacens and S. mitis could differentiate between pancreatic cancer patients and those with pancreatitis, achieving 86% sensitivity and 53% specificity.
Lung Cancer Signatures
For lung cancer detection, researchers have identified bacterial genera including Capnocytophaga and Veillonella as effective biomarkers. The combination achieved 85% sensitivity and 87% specificity for squamous cell lung carcinoma detection, and 79% sensitivity with 90% specificity for lung adenocarcinoma. Other studies have highlighted Acidovorax as an additional biomarker, potentially linked to smoking behaviours and immune suppression.
Colorectal Cancer Detection
The most comprehensive research has focused on CRC, where multiple bacterial species have emerged as powerful diagnostic markers. A recently characterised bacterial gene marker from Lachnoclostrium species showed significant elevation in colorectal adenomas, achieving 48% sensitivity and 79% specificity. However, when combined with additional bacterial species including Fusobacterium nucleatum, Hungatella hathewayi (formerly Clostridium hathewayi), and Bacteroides clarus, the diagnostic performance improved dramatically to 94% sensitivity and 81% specificity for CRC detection.
Individual bacterial species have also shown promise as standalone biomarkers. Clostridium symbiosum alone demonstrated 80% sensitivity and 55% specificity for CRC detection, remarkably outperforming the well-known cancer-associated pathogen F. nucleatum. When researchers analysed C. symbiosum using sophisticated modelling approaches, they achieved AUROC scores of 0.74 for early-stage CRC and 0.76 for all CRC stages – both representing improvements over the current fecal immunochemical test (FIT).
The Promise of Spore-Based Therapeutics
Beyond diagnosis, the microbiome is opening new avenues for cancer treatment through innovative spore-based strategies. Bacterial spores, the dormant forms of certain microorganisms, possess unique properties that make them ideal for targeted cancer therapy.
Precision Drug Delivery
Bacillus coagulans spores have been engineered as sophisticated drug delivery systems. These spores can survive the harsh acidic environment of the stomach, germinate in the gut when activated by specific nutrients, and release their therapeutic cargo precisely where needed. This approach protects chemotherapy drugs from degradation, overcomes intestinal barriers, and enhances tumour-targeting efficiency whilst reducing systemic side effects.
Similarly, Clostridium butyricum spores have been developed for pancreatic cancer treatment, significantly increasing drug accumulation within tumours. The obligate anaerobic nature of certain Clostridium species means they exclusively colonise the oxygen-poor, necrotic regions of solid tumours – nature’s own targeted delivery system.
Reducing Treatment Toxicity
Perhaps most excitingly, spore-based systems offer the potential to reduce chemotherapy’s notorious side effects. By introducing genes that convert harmless prodrugs into toxic derivatives specifically within bacterial spores that colonise tumours, researchers can concentrate cancer-killing effects where they’re needed whilst sparing healthy tissues.
Current Limitations and Future Directions
Despite these promising developments, important limitations remain. The relationship between microbial changes and cancer is complex – it’s often unclear whether altered microbial patterns cause cancer or result from it. This chicken-and-egg scenario has significant implications for using microbiome signatures for early detection.
Additionally, the oral microbiome varies considerably based on age, ethnicity, diet, and lifestyle factors. Larger, more diverse patient populations need study to ensure diagnostic accuracy across all demographic groups.
My Professional Perspective: The Nutrition Connection
As a clinical dietitian specialising in microbiome health, I’m deeply excited by these developments, but I also want to emphasise a crucial point that’s often overlooked in the rush to develop new diagnostics and treatments: the fundamental role of nutrition in maintaining a healthy microbiome.
The microbiome doesn’t exist in isolation – it’s profoundly influenced by what we eat every day. The foods we choose directly shape our microbial communities, influencing their diversity, stability, and function. A diet rich in diverse plant foods, fermented products, and prebiotic fibres supports a robust, balanced microbiome that may be more resistant to the dysbiotic changes associated with cancer development.
Whilst we eagerly await these revolutionary diagnostic tools and treatments, we mustn’t lose sight of the preventive power we already possess. Every meal is an opportunity to nurture our microbial allies. By understanding and respecting the intricate relationship between nutrition and microbiome health, we can take proactive steps today to support our body’s natural defences against disease.
The future of cancer care may indeed lie in harnessing our microbial partners, but the foundation of that partnership is built on the choices we make at every meal. In supporting microbiome health through thoughtful nutrition, we’re not just feeding ourselves – we’re nurturing an entire ecosystem that protects and sustains us in ways we’re only just beginning to understand.
