Gut microbiota: implications for radiotherapy response and radiotherapy-induced mucositis

ABSTRACT

Introduction: Radiotherapy is a mainstay of solid tumor management but can be associated with unacceptable levels of off-target tissue toxicity which impact treatment outcomes and patients’ quality of life. Tumour response to radiotherapy and the frequency and severity of radiotherapy-induced toxicities, especially mucositis, varies among patients. Gut microbiota has been found to modulate both the efficacy and toxicity of some types of cancer chemotherapies and immunotherapies but has yet to be investigated thoroughly in the setting of radiotherapy.

Area covered: In this review, we discuss the potential role of gut microbiota on modulating radiotherapy-induced oral and gastrointestinal mucositis and the anti-tumor response to radiotherapy through modulation of immune responses.

Expert opinion: The gut microbiota plays a major role in the modulation of systemic immune responses, which influence both radiotherapy response and gastrointestinal toxicities such as mucositis. Hence, investigating the gut microbiota link to the variation in radiotherapy responses and toxicities among patients is warranted. Future targeting of these responses with a patient-tailored restoration of optimal microbial composition could lead to a new era of mucositis prevention and enhanced tumor responses.

KEYWORDS:

• Immunomodulation
• microbiota
• mucositis
• radiotherapy

Article highlights

• Radiotherapy is a key treatment modality for solid tumors, but the variation in patients’ response to radiotherapy and severity of radiotherapy-induced mucositis is still largely unexplained.

• Gut microbiota plays a major role in the development and modulation of intestinal and systemic immune responses.

• Previous studies have found that gut microbiota contributes to the pathogenesis of radiotherapy-induced gastrointestinal mucositis.

• Research has revealed that gut microbiota composition can be used as a predictive marker for the development of radiotherapy-induced diarrhea and fatigue.

• Individuals’ gut microbiota composition potentially influences their response to radiotherapy through the modulation of immune responses.

• Future research to investigate gut microbiota impact on the incidence and severity of radiotherapy-induced oral mucositis is warranted with a view to modulate composition to improve cancer therapy outcomes.

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Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.