Predictive and Preventive Potential of Preoperative Gut Microbiota in Chronic Postoperative Pain in Breast Cancer Survivors.

Background: Evidence suggests a potential relationship between gut microbiota and chronic postoperative pain (CPP). This study aimed to explore the predictive and preventive potential of preoperative gut microbiota in CPP in breast cancer survivors.

Methods: In the clinical experiments, we designed a nested case-control study to compared preoperative gut microbiota of breast cancer survivors with and without CPP using 16s rRNA sequencing. The primary outcome was clinically meaningful pain in or around the operative area 3 months after surgery. Logistic prediction models based on previously identified risk factors for CPP in breast cancer survivors were tested with and without differential bacteria to evaluate the model's potential for improvement with the addition of gut microbiota information. In the animal experiments, preoperative fecal microbiota was transplanted from patients with and without CPP to mice, and a spared nerve injury (SNI) model was used to mimic neuropathic pain in CPP. Mechanical hyperalgesia and the expression of markers of spinal microglia and peroxisome proliferator-activated receptor-γ (PPAR-γ) were assessed.

Results: Sixty-six CPP patients and 66 matched controls were analyzed. Preoperative gut microbiota composition was significantly different in the 2 groups at phylus, family, and genera levels. The discrimination of the clinical prediction model (determined by area under the receiver operating characteristic curve) improved by 0.039 and 0.099 after the involvement of differential gut microbiota at the family and genus levels, respectively. After fecal microbiota transplantation (FMT), "CPP microbiota" recipient mice exhibited significantly increased mechanical hyperalgesia and decreased expression of Ppar-γ and arginase-1 (Arg-1) in the spinal cord.

Conclusions: Preoperative gut microbiota has the potential to predict and prevent the development of CPP and plays a causal role in its development via the PPAR-γ-microglia pathway in the spinal cord. Thus, it could be targeted to develop a prevention strategy for CPP in breast cancer survivors.