Small Bowel Cancer (SBC)

Overview

Small bowel cancer encompasses malignancies of the small intestine including adenocarcinomas, neuroendocrine tumors, and stromal tumors. It is classified under Small Bowel Cancer in OncoTree (parent: BOWEL). Small bowel adenocarcinoma has a relatively high frequency of mismatch repair deficiency (MMR-D)/MSI-H compared to colorectal cancer.

Cohorts in the corpus

  • pancan_mimsi_msk_2024: 60 SBC samples in the prospective MMR IHC secondary cohort used to benchmark the MiMSI MSI classifier (pan-cancer MSK-IMPACT cohort, n=5,037 across 42 cancer types). PMID:39746944

Recurrent alterations

  • MLH1, MSH2, MSH6, PMS2: MMR protein loss detected by IHC as the reference standard for MSI-H classification in the MiMSI study; relative proportions among MMR-D SBC tumors not specifically reported. PMID:39746944

Subtypes

  • Small bowel adenocarcinoma (most common; duodenal, jejunal, ileal)
  • Small bowel neuroendocrine tumor
  • Gastrointestinal stromal tumor (GIST) — distinct entity often classified separately

Therapeutic landscape

  • MSI-H detection: MiMSI achieved 100% sensitivity for MSI-H detection in SBC (vs 94.1% for MSISensor), the highest per-cancer sensitivity advantage in the prospective cohort analysis. PMID:39746944
  • Immune checkpoint blockade is FDA-approved for MSI-H/dMMR tumors regardless of histology (pembrolizumab); high MMR-D frequency makes SBC a relevant indication.

Sources

  • PMID:39746944 — Ziegler et al. Nature Cancer 2024. MiMSI deep-learning MSI classifier.

This page was processed by crosslinker on 2026-04-30.