[A Case of Rectal Neuroendocrine Carcinoma That Showed a Sharp Turning Point after Neoadjuvant Radiochemotherapy and Conversion Surgery].

A 45-year-old man presented with the chief complaint of anal discomfort to a previous doctor. The symptoms remained after undergoing seton surgery following the diagnosis of intermuscular anal fistula. CT showed a tumor that was 3 cm in diameter on the right wall of the rectum, and he received a diagnosis of neuroendocrine carcinoma(NEC)based on a biopsy. Subsequently, he was admitted to our hospital. Liver metastasis accompanied NEC, and chemotherapy was performed for stage Ⅳ diagnosis. We detected tumor disappearance after administering 8 courses of CDDP plus CPT-11. However, after 3 months, a 1 cm nodule appeared at the primary lesion, which was considered as recurrence. We selected reintroduction of CDDP plus CPT-11 treatment, but the tumor progressed. CDDP plus VP-16 plus radiation therapy was introduced, and tumor shrinkage was observed without distant metastasis. We judged that radical resection was possible, and performed Miles' operation, total prostate gland resection, and urethra reconstruction. He was discharged on the 28th day after surgery. The pathological findings indicated neuroendocrine small cell carcinoma, and the CRT effect was judged as Grade 2 and curability A. However, he was admitted to the emergency room following convulsions on the 46th day after surgery was performed. CT revealed multiple cerebral metastasis, meningeal dissemination, and liver metastasis. He underwent cyber knife surgery for brain metastasis. Drainage was required for cerebral hypertension due to meningeal dissemination. He died on the 115th postoperative day.