[A Case of Duodenum Dissemination after Surgery for Transverse Colon Carcinoma Which Was Unresponsive to Chemotherapy, but Immunotherapy Was Significantly Effective].

The patient was a 73-year-old woman who received surgery for transverse colon cancer(laparoscopic right hemicolectomy) in December 2014. Histopathologic examination findings were tub2, pT4b, pN1, sH0, sM0, ly2, v0, Stage III a. XELOX 2 courses→FOLFIRI plus panitumumab(Pmab)12 courses was performed after surgery. Stenosis due to duodenum dissemination was observed in the follow-up period(December 2015), and a laparoscopic gastrojejunostomy was performed. Later, the patient's tumor marker value significantly increased, and enlargement of duodenum dissemination was observed by abdominalCT. From April 2016, treatment was switched to mFOLFOX6 plus Pmab and 5 courses were subsequently performed. Still, metastasis to the abdominal wall was observed. According to results of the microsatellite instability test of MSIH, the patient was registered into a clinicaltrialfor pembrolizumab, which is anti-PD-1, and administration began from June. The tumor marker value significantly decreased, and a reduction in the size of the duodenum dissemination over time could also be observed by abdominal CT. Significant tumor reduction was observed, indicating that immune therapy may be significantly effective in some cases.