A Case of Descending Colon Adenocarcinoma with Neuroendocrine Differentiation Successfully Treated with FOLFIRI plus Bevacizumab

We report a case of descending colon adenocarcinoma with neuroendocrine differentiation that was effectively treated with FOLFIRI plus bevacizumab. A 70-year-old man underwent a colonoscopy and was found to have a type 2 tumor of the descending colon. A well-to-moderately differentiated adenocarcinoma was diagnosed by biopsy. A preoperative CT scan showed paraaortic lymph node and liver metastasis, and that the tumor was directly invading the spleen. The patient underwent a left hemicolectomy with resection of the pancreas tail, spleen, and diaphragm. The pathological diagnosis was adenocarcinoma with less than 30% neuroendocrine differentiation in the primary tumor and almost 100% neuroendocrine differentiation in the metastatic lymph nodes. After surgery, FOLFIRI plus bevacizumab treatment was initiated. After 33 treatment cycles, the paraaortic lymph node and liver metastasis disappeared and the patient has remained progression-free to date. Adenocarcinoma with neuroendocrine differentiation of the colon is rare and an effective chemotherapy has not yet been established. We report this case with a review of the literature.