BRAF V600E-mutated Colorectal Neuroendocrine Carcinoma Effectively Treated with a Chemotherapy Protocol for BRAF-mutated Metastatic Colorectal Cancer.

Metastatic colorectal neuroendocrine carcinoma (NEC) is often treated using a chemotherapy protocol for small-cell lung cancer; however, the prognosis is extremely poor. A 55-year-old woman with BRAF V600E-mutated transverse colon NEC and liver metastases underwent colectomy followed by FOLFOXIRI plus bevacizumab. Consequently, the liver metastases markedly shrank. Owing to later worsening of the liver metastases, she received encorafenib and binimetinib plus cetuximab. Despite discontinuing binimetinib due to myalgia, she had a long-term response with a progression-free survival of 14 months and an overall survival of more than 27 months. A chemotherapy protocol for BRAF-mutated metastatic colorectal cancer may be a treatment option for BRAF V600E-mutated colorectal NEC.