Background and Aims Mixed adeno-neuroendocrine carcinoma (MANEC) is a rare and highly malignant tumor. In recent years, the incidence of colorectal MANEC has shown a certain growth trend. This study summarizes the clinicopathologic data as well as the diagnosis and treatment process of colorectal MANEC cases treated over the past decade, with the aim of increasing awareness of this disease and thereby standardizing its treatment and management.Methods The clinical data of 13 patients diagnosed with colorectal MANEC through pathological and immunohistochemical examination of surgical specimens from January 2010 to March 2023 were retrospectively analyzed.Results Among the 13 patients with colorectal MANEC, 10 were male (76.9%), with an average age of 65.1 years. The most common complaints were bloody stools and changes in stool characteristics, with 61% of patients showing positive physical signs. All patients were found to have thickening of the bowel wall through CT or MRI, and a mass was detected through endoscopy, which led to preoperative histopathological reports. However, only 2 cases had a preoperative pathological report indicating the presence of neuroendocrine components, and additional whole-body PET/CT imaging using ¹⁸F-octreotide (¹⁸F-OC) as the imaging agent indicated increased somatostatin receptor expression in the thickened bowel wall and surrounding lymph nodes. All 13 patients underwent surgical treatment, with 3 cases receiving preoperative neoadjuvant therapy. The majority of patients were classified as stage Ⅲ or Ⅳ after surgery (84.6%). Common sites of metastasis included per-intestinal lymph nodes and the liver. The average tumor size was 4 cm × 3.4 cm × 2.6 cm, and 84.6% (11/13) of tumors were ulcerative. In 92.2% of cases, the tumors were moderately to poorly differentiated adenocarcinomas. Seven patients received postoperative drug therapy. The survival periods for 8 patients were obtained, and the average survival was 20.6 months with a median survival of 13.5 months. Two patients had a postoperative survival exceeding 3 years.Conclusion Colorectal MANEC has a generally unfavorable prognosis, and survival may be primarily associated with clinical pathological stage and the presence of distant metastasis. The preoperative pathological diagnosis rate is relatively low, and the use of octreotide-based PET/CT imaging can increase the detection rate of this disease. The main treatment approach is surgery, with chemotherapy as an adjuvant therapy. Further clinical studies are needed to determine whether a combination chemotherapy regimen targeting both the neuroendocrine and adenocarcinoma components, as well as immunotherapy, can provide advantages in the treatment of advanced colorectal MANEC.