Small Bowel Cancer: Implications of Preoperative Work-Up on Surgical Strategy.

Small bowel cancers comprise a heterogeneous group of malignancies, making diagnosis and treatment challenging. This study aimed to evaluate the ability of preoperative diagnostic work-up to predict clinical and histopathological findings, facilitate subgroup identification, and support tailored, individualized surgical strategies. This retrospective single-center analysis included all patients operated 2015-2024 for suspected small bowel cancer at a tertiary referral center. Preoperative assessments-including diagnostic evaluation of tumor type, disease extent, and anatomical localization-were compared to intraoperative findings and final histopathological results. Of 187 operations, 59 (32%) were right colectomies, 50 (27%) robotic/laparoscopic procedures and 36 (19%) emergencies. Preoperative symptoms were present in 156 (83%) patients. CT scans were performed in 184 (98%), somatostatin receptor imaging (SRI) in 120 (64%), endoscopy in 92 (49%), and biopsy in 74 (40%). Small intestinal neuroendocrine tumors (siNET) were found in 108 (58%) patients, carcinomas in 24 (13%), metastatic tumors in 17 (9%), gastrointestinal stromal tumors in 13 (7%), benign lesions in 13 (7%), lymphomas in 8 (4%), and desmoid tumors in 4 (2%). The preoperative tentative tumor entity was correct in 118 (63%). CT sensitivities for mesenteric and peritoneal metastases were 65% and 9%, respectively. SRI was positive in 83/92 siNET and 6/28 non-NET. Mesenteric metastases were found in 99 (95%) siNET patients. SRI failed to identify mesenteric dissemination in 24 (27%) siNET patients. Among patients with siNET, 18 (17%) had liver metastases and 18 (17%) had peritoneal metastases. SiNET multifocality was associated with distant metastatic status (p < 0.001). Pathologists found 313 luminal siNET, 17 tumors were missed by intraoperative palpation, 51 by SRI and 156 by CT. All siNET were in the ileum. Terminal compared to middle/upper ileum siNET were more often solitary (39/42 [93%] vs. 31/60 [52%]; p < 0.001) and had less often advanced mesenteric disease (N2) (9/44 [20%] vs. 31/58 [53%]; p < 0.001). Preoperative work-up of small bowel cancer is often inaccurate, particularly when it comes to identification of bowel tumors and metastases. Intraoperative palpation of the bowel and its mesentery and inspection of the peritoneum remain essential to facilitate an adaptive surgical strategy.