Malignant Small Bowel Neoplasms: A 20-Year Retrospective Analysis in a Tertiary Center

Malignant small bowel neoplasms are rare entities, and knowledge about them remains limited due to their histological diversity and the challenges associated with their investigation. However, their rising incidence has generated increasing clinical and research interest. This study aimed to describe the demographic and clinical characteristics of patients with malignant neoplasms of small bowel and the evolution in their diagnosis over 20 years in a tertiary center.

Single-center retrospective study of data of patients with malignant small bowel neoplasms diagnosed between 2001 and 2020 in a tertiary hospital was performed. Statistical analysis was performed with SPSS version 29.0 (significance level ≤0.05).

Out of 135 patients included, 57% were male. Eighty-nine neoplasms (65.9%) were found in the jejunum/ileum. Adenocarcinomas were the most frequently diagnosed neoplasms (31.1%), followed by neuroendocrine tumors (28.1%). At the time of diagnosis, the majority of patients (80.7%) were symptomatic, with severe complications - including obstruction, hemorrhage, or perforation - occurring in 55.4% of cases. Diagnosis typically involved CT scan (40.7%) or upper digestive endoscopy (22.2%); notably, 22.2% patients still required surgery for diagnosis. Diagnoses were mainly made between 2011 and 2020 (65.9%). Between 2001 and 2010, the most common diagnosed tumors were adenocarcinomas (37.0%), whereas between 2011 and 2020, the most frequently diagnosed malignant neoplasms were neuroendocrine tumors (37.1%). The distribution of histological types differed significantly over the years (p = 0.016). Adenocarcinoma had a higher mortality rate (54.8%) compared to neuroendocrine tumors (7.9%).

Given the rarity of these tumors, the cohort of malignant small bowel neoplasms collected at this tertiary center over a 20-year period represents a substantial sample. More than half of patients were symptomatic at diagnosis, despite diagnostic advances over the years. In the last 10 years of the study, there has been an increase in incidence as well as in 5-year survival rates, possibly due to the higher incidence of neuroendocrine tumors and the lower incidence of adenocarcinomas. Notably, the diagnosis of each histological neoplasm type differed significantly statistically over the years, with neuroendocrine tumors being the most diagnosed in recent years.