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🌱 來自: gastric cancer

Pathology of gastric cancer

Lauren histologic classification

• Intestinal:
  • Tumor cells arranged in tubular or glandular formations,
  • spreads through gastric wall as part of a tumor mass
• Diffuse:
  • Defective intercellular adhesion molecules allow tumor cells to invade w/o formation of tubules or glands;
  • spreads as discohesive cells throughout stomach wall;
  • highly metastatic;
  • signet-ring histology is → a poor prognostic factor

WHO classification: Tubular, papillary, mucinous, poorly cohesive incl. signet ring, adenosquamous, small cell, undifferentiated, squamous cell

• The CA genome atlas 4 subtypes:
  • EBV-positive (w/ recurrent PIK3CA muts,
  • higher prevalence of DNA hypermethylation),
  • microsatellite instability (MSI),
  • chromosomal instability (CIN) (↑ receptor tyrosine kinases incl. VEGFR2),
  • genomically stable (GS)

Biomarkers w/ clinical implications

• HER2 overexpression:
  • Determined by HER2 IHC (3+), IHC equivocal (2+), & FISH amp, or HER2 gene amplification;
  • 10-20% of gastric adenoCAs MMR:
    • Determined by IHC for MLH1, MSH2, MSH6, PMS2 proteins PD-L1: Positive if combined positive score (CPS) ≥1;
  • unclear utility as responses seen w/ checkpoint inhibition in PD-L1 (-) tumors & significant interobserver variability EBV:
    • Gold standard is → EBV-encoded RNA in situ hybridization (EBER-ISH) NGS: Tumor sequencing for other targets (eg, NTRK)