A post hoc analysis of the prospective REVEAL study suggests that preoperative gut microbiome composition may contain prognostic information for patients with early-stage colorectal cancer. The study included 204 patients with stage I–III CRC, with an overall recurrence rate of 21%, and analyzed fecal samples using 16S rRNA gene sequencing.
Patients who subsequently developed locoregional recurrence had different microbial profiles from those who did not. In particular, higher preoperative abundance of Porphyromonas was associated with a greater risk of recurrence, with a reported hazard ratio of 2.80. Several other bacterial genera were associated with locoregional or distant recurrence, although Porphyromonas was the only genus that remained implicated when patients were stratified by abundance.
The findings suggest that stool microbiome profiling could eventually complement conventional postoperative surveillance. However, the study is not yet sufficient for clinical implementation. The article highlights the need for external validation, species- and strain-level analysis, and studies testing whether modifying the microbiome can actually reduce recurrence.