From the Research
In ileal neuroendocrine tumors (NETs), mesenteric lymph node metastases typically occur before liver metastases. The pattern of spread for ileal NETs generally follows a predictable sequence where the tumor first metastasizes to regional mesenteric lymph nodes before spreading hematogenously to the liver. This pattern reflects the lymphatic drainage of the ileum, which directs tumor cells first to the mesenteric nodes. Studies have shown that approximately 80-90% of patients with ileal NETs have mesenteric lymph node involvement at diagnosis, while liver metastases are present in about 40-60% of cases, as seen in a study published in the Journal of surgical oncology 1. The presence of mesenteric lymph node metastases is often associated with a desmoplastic reaction that can cause mesenteric fibrosis and intestinal obstruction, even when the primary tumor is small. This sequential pattern of spread is important for staging, treatment planning, and surveillance strategies in patients with ileal NETs, as the extent of disease significantly impacts prognosis and management decisions. Some studies have reported on the incidence of mesenteric lymph node metastasis in patients with right-sided colon cancer, and the clinical significance of peri-ileal lymph node metastasis in these patients 2. However, the most recent and highest quality study on this topic is the one published in 2019, which found that mesenteric lymph node metastases are a common occurrence in ileal NETs and are associated with a poor prognosis 1. Therefore, mesenteric lymph node metastases should be considered the first site of metastasis in ileal NETs, followed by liver metastases. Key points to consider include:
- The pattern of spread of ileal NETs follows a predictable sequence, with mesenteric lymph nodes being the first site of metastasis
- The presence of mesenteric lymph node metastases is associated with a desmoplastic reaction and poor prognosis
- The extent of disease significantly impacts prognosis and management decisions in patients with ileal NETs
- Mesenteric lymph node metastases should be considered the first site of metastasis in ileal NETs, followed by liver metastases, as supported by the study published in the Journal of surgical oncology 1.