Primary neuroendocrine carcinoma (NEC) of the anal canal is a rare, highly malignant tumor with a poor prognosis. Despite the standard first-line treatment with etoposide or irinotecan combined with cisplatin, effective second-line therapies are lacking. In 2019, Japan approved cancer genome profiling (CGP) tests for solid tumors to enhance genomic understanding. We present the case of a 79-year-old woman with NEC of the anal canal, treated with etoposide, carboplatin, and amrubicin. As Post-standard therapy, CGP suggested pemigatinib, a tyrosine kinase inhibitor; however, the patient died before receiving it. This case highlights the potential of personalized medicine to improve outcomes in such cases.

Colorectal neuroendocrine carcinoma (NEC) is a rare tumor that demonstrates aggressive growth pattern with ingrowth into the tract, metastasis to the other organs, and invasion to the surrounding organs; these clinical characteristics result in poor prognosis. Surgical resection appears as an effective approach; however, because it is difficult to accurately diagnose NEC during the early stage and owing to its aggressive growth pattern, development of a reliable standard chemotherapy regimen and management strategies are essential.

Here, we report the case of patient with NEC showing an aggressive growth pattern that resulted in the rupture of the tumor to the outside the colon after stenting of the internal colonic stenosis. In addition, the tumor invaded into the duodenum, thereby causing duodenal stenosis that required an additional stent in the duodenum. This aggressive growth pattern is one of the main features of the NEC that is different from adenocarcinoma. To clarify the clinical characteristics, we reviewed 60 recently reported cases, including data on tumor location, size, treatment, and prognosis.

We consider that the information presented here is of great significance for the diagnosis, treatment, and management of symptoms of the patients with NEC.

Endocrine cell carcinoma, according to the Japanese classification criteria for colorectal cancer, corresponds to neuroendocrine carcinoma (NEC) and mixed adenoneuroendocrine carcinoma (MANEC), as defined in the 2010 World Health Organization (WHO) classification. We retrospectively reviewed the clinical features of patients with these tumors diagnosed and treated at our institution.

The clinicopathological features of endocrine cell carcinomas of the colon and rectum diagnosed by neuroendocrine markers from January 2000 to December 2012 were retrospectively evaluated in 12 patients.

Surgical specimens were obtained from eight of the 12 patients. MANEC was diagnosed in six patients and NEC in one. One tumor was unclassifiable. The tumors were not resected in four patients, and all died within 3 months. Of the eight patients who underwent resection, four received an R0 resection, two of whom underwent adjuvant chemotherapy and survived more than 5 years. One patient who underwent an R2 resection and continuous chemotherapy survived for 53 months. One patient with NEC underwent surgery and radiotherapy, and died 17 months later.

Most endocrine cell carcinomas of the colon and rectum reviewed were MANECs. Though their prognosis was generally poor, chemotherapy may be effective in some patients.