Synergistic effect of photodynamic therapy with multimodal therapy achieves anus preservation in MSS ultra-low rectal cancer—A case report and literature review

The preservation of the anus in ultra-low rectal cancer (ULRC) surgery presents considerable clinical challenges. While combined neoadjuvant therapy is considered a pivotal treatment strategy, its effectiveness is constrained by factors such as anatomical location, postoperative complications, systemic toxic reactions, and tumor drug resistance. Photodynamic therapy (PDT), as a localized treatment modality, operates through multiple mechanisms, including the targeted eradication of tumor cells, disruption of the tumor vascular system, reversal of drug resistance, and activation of antitumor immune responses. This article presents a case study of a patient with stage IIIb (cT4N1Mx), microsatellite stable (MSS) ULRC, who successfully achieved tumor downstaging and underwent anus-preserving surgery following a comprehensive treatment regimen. This regimen included PDT, systemic therapy, da Vinci robot-assisted anus-preserving surgery, and anastomotic stent implantation. The patient has achieved a progression-free survival (PFS) exceeding 14 months. At present, the patient exhibits satisfactory defecation function, and no complications, such as anastomotic fistula, have been observed.