A virulent bacterial signature is associated with the development of recurrence following colorectal cancer surgery.

The primary treatment for non-metastatic colorectal cancer is surgical resection. Despite the use of neoadjuvant and/or adjuvant chemoradiation, up to 30% of patients undergoing surgery for colorectal cancer will develop a postoperative recurrence. Why patients develop postoperative tumors despite all known cancer being resected at the time of surgery is largely unknown, and novel biomarkers that can predict the development of recurrence are lacking. Here, we report a unique bacterial signature present in the gut during the perioperative period that is strongly associated with the development of postoperative tumors. By studying patients undergoing resection for colorectal cancer, we demonstrate that the gut microbiome on the day of surgery is enriched with collagenase-producing bacteria in patients who later develop a recurrence. This bacterial community demonstrated enhanced antimicrobial resistance, was not eradicated by the standardized perioperative bowel preparation, and could promote cancer cell migration and invasion. Our study establishes that microbiota may contribute to postoperative colorectal cancer recurrence and serve as a prognostic biomarker for postoperative oncologic outcomes.