A novel approach in colon cancer treatment: successful conversion of locally advanced colon cancer using endoscopic rendezvous technique combined with multimodal therapy—A case report and literature review

This case report explores the potential of endoscopic photodynamic therapy (PDT) to downstage locally advanced colon cancer (LACC) and enhance patient quality of life. A young female with obstructive LACC, unresponsive to CapeOX chemotherapy, underwent emergency colostomy followed by dual-route endoscopic PDT. Subsequent neoadjuvant therapy, including TAS-102, targeted agents, and immunotherapy, led to a partial tumor response. This enabled fluorescence-guided radical resection and stoma reversal. The patient achieved favorable postoperative recovery, with symptomatic relief, decreased tumor marker levels, and no evidence of disease (NED). This case demonstrates that endoscopic PDT combined with multimodal systemic therapy can facilitate successful conversion surgery and bowel function restoration in treatment-refractory LACC.