Role of Urinary Microbiota in Patients with Non-Muscle-Invasive Bladder Cancer

By Shane Whitney - Last Updated: January 20, 2022

Colleagues from the Nanfang Hospital of the Southern Medical University in Guangzhou, China, and co-lead contributors, Yifeng Qiu and Yubo Gao, examined the influence of the urinary microbiota on immune evasion and tumor growth in patients with non-muscle-invasive bladder cancer via analysis of FoxP3+ regulatory T cells, expression of Ki-67, and clinical prognosis in patients. According to their study, published in Human Cell, patients with lower urinary microbial diversity had longer recurrence-free survival compared to patients with higher diversity.

The study’s authors theorized that “perturbation of urinary microbiota may induce immune evasion and tumor growth, eventually contributing to unfavorable outcomes.

The study retrospectively analyzed a total of 40 male patients, of which 12 had previous recurrence. Microbial compositions of preoperative urine samples were assessed with 16s rDNA sequencing. Additionally, alpha and beta diversities, intratumoral infiltration of FoxP3+ regulatory T cells, Ki-67 expression, and bacteria specifically associated with recurrence were all assessed.

According to the investigators, patients with recurrence had higher alpha diversity compared to those without recurrence (Shannon Index, p = 0.0007; Simpson Index, p = 0.0004). Furthermore, “distinct beta diversity” was seen between the recurrence and non-recurrence groups (weighted Unifrac, p = 0.02; unweighted Unifrac, p = 0.001). Analysis showed that the patients with recurrence had markedly higher Pseudomonas, Staphylococcus, Corynebacterium, and Acinetobacter genera. Patients with higher alpha diversity had elevated expression of Ki-67 compared with those with lower alpha diversity (p = 0.0194). The authors noted that microbial diversity was not associated with infiltration of FoxP3+ regulatory T cells (p = 0.1653).

The study’s authors concluded that urinary microbiota may play a “casual role” in modulating antitumor response and survival in patients with bladder cancer, but they stated that additional research is needed to confirm their suggestion.