How should increased Fusobacterium spp. in feline GI lymphoma be interpreted?

• A. It may represent either a consequence of the malignancy or a contributor to IBD → LSA progression; causality not established
• B. It proves Fusobacterium causes lymphoma
• C. It is solely a bystander with no disease relevance
• D. It results from antibiotic therapy

Answer: (A)

Increased Fusobacterium spp. in feline GI lymphoma is best viewed as an association rather than proof of causation. The tumor and its surrounding inflammatory environment can alter the gut mucosa, immune responses, and luminal conditions, creating a niche where certain bacteria like Fusobacterium thrive. At the same time, Fusobacterium has biological plausibility to participate in inflammatory signaling and processes that could hypothetically contribute to disease progression from inflammatory processes toward neoplasia. But this does not establish that Fusobacterium causes lymphoma. It could be a consequence of the malignancy, a contributor to ongoing inflammation that facilitates progression, or a bystander reflecting altered gut ecology; antibiotics or other factors could also influence the microbial landscape. The correct interpretation acknowledges the uncertainty: causality has not been established, and the finding could represent either a consequence of the tumor or a potential contributor to disease dynamics, without proving Fusobacterium as the driver.