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Source created 2026-08-25 · updated 2026-08-25
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ASCRS Ch34 - Gastrointestinal Stromal Tumors, Neuroendocrine Tumors, and Lymphoma

Chapter 34, "Gastrointestinal Stromal Tumors, Neuroendocrine Tumors, and Lymphoma," ASCRS Textbook of Colon and Rectal Surgery, 4th edition. Authors: Alavi K, Boutros M. Book pp. 587–600 (title page through References).

Textbook reference chapter (not primary literature), closing out Part III ("Malignant Disease"). Three distinct sections: GISTs (whole-GI-tract, not small-bowel-specific), neuroendocrine tumors of the midgut and hindgut (explicitly excluding appendiceal NETs, deferred to Chapter 33), and colorectal lymphoma.

GISTs

Substantially corroborates the wiki's existing Gastrointestinal Stromal Tumors (GIST) page (previously sourced from Sabiston's small-bowel-neoplasm chapter) with consistent biology, staging, and imatinib-based treatment framework. Adds:

  • Molecular associations not previously captured: SDH-deficient GIST, Carney triad (gastric GIST + pulmonary chondroma + paraganglioma), Carney-Stratakis syndrome (GIST + paraganglioma, germline SDH mutation), and NF1-associated GIST (typically small-bowel, multifocal, KIT/PDGFRA wild-type) — a distinct molecular subgroup from the classic KIT exon 11/exon 9 and PDGFRA-mutant GISTs.
  • Incidence/distribution restated for the whole GI tract (rather than small-bowel-specific): median age 65, gastric 56%, small bowel 32%, colorectal 5–10% — broadly consistent with, and extending, the existing page's small-bowel-focused framing (gastric 60%/jejunoileal 30%/duodenal 5%).
  • Rectal GIST-specific surgical technique: transanal platforms (TEM, TEO, TAMIS) for low-rectal/anorectal GISTs, with local excision vs. radical resection recurrence-rate comparisons — local excision favored where oncologically feasible given equivalent recurrence outcomes in appropriately selected small/low-risk lesions, sparing patients a more morbid radical resection. Not previously covered on the existing page (which had no rectal-GIST-specific technique detail).
  • Neoadjuvant imatinib use, per Cavnar et al.'s case series, for tumors requiring extensive surgery — reduces tumor bulk prior to resection, allowing more limited surgery; corroborates the existing page's brief neoadjuvant-imatinib mention with a named primary-source series.
  • Adjuvant imatinib trial evidence — named trials (existing page cited "multiple randomized trials" without naming them):
  • ACOSOG Z9001: adjuvant imatinib vs. placebo after resection of primary GIST ≥3 cm — established the benefit of 1 year of adjuvant imatinib in reducing recurrence.
  • EORTC 62024: adjuvant imatinib (2 years) vs. observation — informed duration questions.
  • Scandinavian Sarcoma Group VIII (SSG VIII): 3 years vs. 1 year of adjuvant imatinib in high-risk GIST — 3 years significantly improved recurrence-free and overall survival over 1 year, the basis for the current 3-year high-risk adjuvant recommendation.
  • PERSIST-5: single-arm study of 5 years of adjuvant imatinib in high-risk GIST, exploring whether extending beyond 3 years further improves outcomes.
  • RFA for hepatic GIST metastases: radiofrequency ablation as an option for limited hepatic metastatic disease, alongside systemic TKI therapy — not previously mentioned on the existing page.

Neuroendocrine tumors (midgut and hindgut)

Explicitly excludes appendiceal NETs ("covered in Chap. 33" per the chapter text — corroborates the wiki's existing appendiceal-NET-specific handling on Appendiceal Neoplasms). General NET biology/diagnosis content (histology, WDNET/PDNET terminology, CgA/synaptophysin biomarkers, carcinoid syndrome mechanism and right-sided valvular heart disease) closely corroborates the existing Small Bowel Neuroendocrine Tumors (NETs) page — see that page for the detailed primary-source trial synthesis (PROMID, CLARINET, RADIANT-4, NETTER-1), which this chapter does not materially extend. The chapter's genuinely new content, relative to the wiki's existing (small-bowel- focused) NET coverage, is its colonic/rectal (hindgut) NET-specific staging and treatment algorithm — backing a new dedicated page, Colonic and Rectal Neuroendocrine Tumors:

  • Incidence/distribution: rectum is the single most common GI-NET site overall.
  • 68Ga-DOTA-PET/CT: 93% sensitivity / 96% specificity for GI NETs — closely corroborates (not identical to) the existing page's cited 95%/95% figures from a smaller study; both point the same direction (DOTATATE-based PET clearly outperforming FDG-PET for well-differentiated NETs).
  • Biochemical workup: CgA and urinary 5-HIAA, with Table 34.3 listing dietary/medication interferers with 5-HIAA testing (e.g., serotonin-rich foods — bananas, avocados, walnuts, tomatoes — and drugs affecting serotonin metabolism) — a practical testing-methodology detail not on the existing page.
  • TNM staging (Tables 34.1–34.2): colon and rectal NETs staged with their own site-specific TNM criteria, distinct from both the general colorectal-adenocarcinoma TNM system and the appendiceal- NET-specific system in Chapter 33.
  • Treatment algorithm by size (Table 34.4, Fig. 34.4): for rectal NETs, endoscopic resection is favored for very small lesions, transanal excision/TES for a middle size tier, and radical (oncologic) resection for larger or higher-risk lesions — the 1–2cm zone is a genuine decision point requiring individualized assessment of depth of invasion, grade, and other risk features, broadly analogous to (though a distinct algorithm from) the appendiceal-NET 1–2cm decision zone on Appendiceal Neoplasms.
  • Prognosis: hindgut NETs (rectal/colonic) have a much better prognosis than midgut NETs — reframes/extends the existing Small Bowel NETs page's prognosis section, which is midgut-focused.

Lymphoma

The wiki had no dedicated colorectal-lymphoma page before this chapter — only a brief small-bowel- focused lymphoma passage on Small Bowel Neoplasms (which itself flagged this exact gap as an open item). Backs a new dedicated page, Colorectal Lymphoma — the wiki's first dedicated treatment of this topic. See that page for full content (incidence/distribution, histologic subtypes/WHO classification, Dawson criteria, Ann Arbor staging, treatment by localized/advanced stage and cell lineage, special scenarios).