Is fecal matter (fecal microbiota transplantation (FMT)) a recommended treatment approach in oncology (cancer treatment)?

Use of Fecal Microbiota Transplantation in Oncology

Fecal microbiota transplantation (FMT) is NOT currently recommended for routine use in oncology outside of clinical trials or compassionate use programs, as current guidelines only support FMT for recurrent Clostridioides difficile infection (CDI), not for cancer treatment itself. 1

Current Guideline-Based Indications

Established Use: CDI in Cancer Patients Only

• FMT achieves nearly 90% clinical cure rates for recurrent CDI and is recommended as standard treatment for this specific indication 1
• In immunocompromised cancer patients with recurrent CDI, FMT can be used with comparable success rates (85% in malignancy patients) to immunocompetent individuals (83.4%) 1
• Serious adverse event rates in cancer patients receiving FMT for CDI are similar to immunocompetent patients (3% in malignancy cohorts vs 11% in general population) 1

Investigational Status for Cancer Treatment

• International consensus guidelines explicitly state that FMT for cancer treatment requires further studies before clinical recommendation and should be limited to research settings or compassionate use in the absence of alternative therapeutic options 1
• The British Society of Gastroenterology (2024) confirms FMT has no place in oncology management outside of CDI treatment unless within clinical trial contexts 1
• The American Gastroenterological Association (2024) does not recommend FMT for cancer treatment in routine practice 1

Compassionate Use Framework

When to Consider (Strict Criteria Required)

FMT may be considered in oncology only when ALL of the following conditions are met: 1

• Patient cannot be enrolled in an ongoing clinical trial
• Multidisciplinary team (MDT) discussion and approval obtained, including senior oncology and gastroenterology/infectious disease representation
• Biological rationale exists to justify consideration
• Patient faces significant clinical compromise with limited alternative therapeutic options
• Patient fully understands risks versus benefits compared to other treatments
• Clear definition established pre-treatment for what constitutes success or failure
• Strategy agreed upon for potential subsequent FMTs based on initial response

Critical Safety Considerations in Cancer Patients

Severely immunocompromised patients should be excluded from FMT, defined as: 1

• Active solid tumors or hematologic malignancies undergoing active treatment
• Patients receiving chimeric antigen receptor T-cell therapy
• Hematopoietic cell transplant recipients who are neutropenic
• Any neutropenia present
• Severe primary immunodeficiency
• Advanced or untreated HIV infection (CD4 <200/mm³)

Mildly or moderately immunocompromised cancer patients may be considered with appropriately screened donor stool and enhanced safety monitoring 1

Emerging Research Context (Not Yet Clinical Practice)

Potential Mechanisms Under Investigation

• Gut microbiota modulation may enhance immune checkpoint inhibitor (ICI) response in select patients 2, 3
• FMT might reshape the tumor microenvironment and enhance immune responses 3, 4
• Possible roles in preventing graft-versus-host disease and treating immunotherapy-induced colitis 5

Why Guidelines Remain Restrictive

• Lack of knowledge about transferability of tumorigenesis through FMT remains a major concern 1
• Unknown long-term side effects of FMT in cancer patients 1
• Insufficient data on optimal donor-recipient pairing, timing, dosing, and administration routes for oncology applications 1
• No standardized protocols exist for FMT preparation, frequency, or duration in cancer treatment 1
• Theoretical risks of pathogen transmission in immunocompromised hosts 5

Common Pitfalls to Avoid

• Do not offer FMT for cancer treatment outside of CDI indication without MDT approval and documented compassionate use justification 1
• Do not use FMT in severely immunocompromised patients as defined above 1
• Do not proceed without comprehensive donor screening per established protocols 1
• Do not confuse promising preclinical data with clinical readiness—animal studies showing FMT benefits with immunotherapy have not yet translated to validated human protocols 2, 3

Documentation Requirements for Compassionate Use

• Comprehensive documentation of clinical outcomes must be maintained 1
• Data collection should include patient demographics, cancer type and stage, prior treatments, FMT protocol details, and longitudinal outcomes 1
• Reporting to institutional review processes or registries is essential to build knowledge base 1