Background
Multimodal individualized treatment concepts are becoming increasingly important in the treatment of metastatic rectal cancer. Rectum-sparing resections of the primary tumor after a good response to systemic therapy in patients with metastatic rectal cancer have so far only been described in isolated cases as part of liver-first strategies.1 Data on endoscopic resection procedures in metastatic rectal cancer are currently lacking.
The aim of this article is to demonstrate the potential of endoscopic intermuscular dissection (EID) as an effective organ-preserving treatment option within the framework of a multimodal therapy concept following successful systemic therapy.
Case report
A 20-year-old patient with microsatellite-stable hepatically metastasized rectal carcinoma (KRAS G13D mutation, BRAF wild type) was treated with a total of seven cycles of FOLFOXIRI, the first five of which were combined with Bevacizumab. With an excellent response to therapy, including a reduction in the size of the local lesion from 30 to 15 mm and regression of the liver metastases. With no involved regional lymph nodes on MRI our interdisciplinary tumor conference decided on an individualized approach involving endoscopic resection of the primary tumor followed by evaluation of a possible liver transplant, analogous to the TransMet study.2
To increase the likelihood of R0 resection, EID of the residual lesion was performed at 12 cm from the anal verge, with endoscopic dissection between the circular and longitudinal muscles. Compared to EMR or ESD, this allows even deeper infiltrating carcinomas to be removed from healthy tissue. The EID was performed without technical or post-procedural complications. The resulting defect was completely closed using an endoscopic suture system (SutuArt, Olympus, Japan). Histopathological examination showed complete resection of the carcinoma in healthy tissue (vital tumor cell content 10%, regression grade 3 according to Dworak, ypT1, sm2 with an infiltration depth of 800 μm, L0, V0). The plan now is to continue systemic therapy and refer the patient to a liver transplant center.
Conclusion
The described case illustrates that in metastatic rectal carcinomas that respond well to systemic therapy EID enables a safe resection of the local tumor with organ preservation. EID thus represents a possible addition to a multimodal therapy concept in suitable patients.