The key finding
A 2025 review published in the World Journal of Surgical Oncology reveals that the balance of microorganisms living on your skin — your skin microbiome — may play a significant role in the development and progression of cutaneous squamous cell carcinoma (cSCC), the second most common type of skin cancer. While ultraviolet radiation has long been recognized as the primary driver of genetic changes leading to cSCC, researchers now understand that disruptions in the skin’s microbial community, combined with immune system responses, also contribute to this disease process. Certain bacteria and viruses, particularly Staphylococcus aureus and human papillomavirus, have been linked to cSCC progression through their effects on immune function.
What the study looked like
This was a comprehensive literature review examining existing research on the relationship between the skin microbiome, immune system function, and cutaneous squamous cell carcinoma development. The authors analyzed studies investigating how skin-dwelling microorganisms and their metabolic byproducts interact with various components of the immune system, including innate immune cells (the body’s first-line defenders), T cells (specialized white blood cells), and signaling molecules called cytokines. The review specifically examined evidence regarding two organisms frequently associated with skin cancer: Staphylococcus aureus bacteria and human papillomavirus. The researchers also explored how beneficial skin microbes might antagonize disease-associated pathogens and whether manipulating the skin microbiome could offer new treatment approaches.
Why researchers think this happened
The authors propose that the skin microbiome influences cSCC progression through multiple immune-mediated pathways. Microorganisms living on the skin produce metabolites — chemical compounds generated during their normal life processes — that can either stimulate or suppress immune responses. When the microbial community becomes imbalanced (a state called dysbiosis), this disruption may alter immune surveillance in ways that allow cancerous cells to evade detection and destruction. Specific pathogens like Staphylococcus aureus and human papillomavirus may directly interfere with immune cell function, creating an environment more permissive to tumor growth. The review builds on growing recognition in cancer research that microbial communities throughout the body can influence tumor development, extending concepts previously explored in gut microbiome research to the skin. The authors suggest that beneficial microorganisms normally present on healthy skin may compete with cancer-associated pathogens, potentially explaining why microbial diversity appears protective.
How to read this carefully
This review synthesizes existing research rather than presenting new experimental data, meaning its conclusions depend on the quality and consistency of the underlying studies. The relationship between skin microbes and cancer is correlational — we cannot yet definitively say that microbial imbalances cause cSCC, only that they’re associated with disease progression. Human skin harbors hundreds of bacterial species in complex ecosystems that vary by body location, age, and individual genetics, making it challenging to identify universal patterns. Most mechanistic studies explaining how microbes influence cancer have been conducted in laboratory settings or animal models, which may not perfectly reflect human disease. The review focuses on potential mechanisms but doesn’t provide clinical trial data demonstrating that microbiome interventions actually prevent or treat cSCC in humans.
What this means for everyday life
This emerging research adds another dimension to skin cancer prevention beyond sunscreen and UV protection. While we shouldn’t overinterpret these findings, they suggest that maintaining a healthy, diverse skin microbiome might support the immune system’s natural cancer surveillance mechanisms. Given this connection, it might be worth considering whether aggressive antibacterial products that disrupt beneficial skin bacteria could have unintended consequences, though this remains speculative. The finding that certain beneficial microbes may antagonize cancer-associated pathogens raises intriguing possibilities for future preventive approaches, though such interventions remain experimental. For now, this research reinforces that skin health involves complex interactions between our cells, immune system, and microbial companions — a reminder that protection against skin cancer likely involves multiple strategies working together rather than any single intervention.