Oncology
GI Cancer Screening & Management
Oncology

GI Cancer Screening & Management

CRC screening, pancreatic CA, GIST, carcinoid.

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◆Colorectal cancer screening

  • •Average risk: start at 45 (USPSTF 2021, lowered from 50)
  • •Options: colonoscopy q10y, FIT annually, sigmoidoscopy q5y + FIT q3y, Cologuard (multi-target stool DNA) q3y
  • •FHx CRC in first-degree relative <60: start at 40 OR 10 years before relative's dx (whichever earlier); repeat q5 yr
  • •Lynch syndrome: colonoscopy q1–2y starting age 20–25
  • •Stop at age 75 if life-expectancy limited

◆Symptomatic CRC

  • •Age >50 + weight loss + iron deficiency anemia + change in bowel habits = colonoscopy (NOT FOBT — that's screening)
  • •Confirmed CRC → CT abdomen/pelvis for staging
  • •Liver mets of unknown primary → consider colorectal source

◆Pancreatic adenocarcinoma

  • •Painless jaundice + weight loss + pruritus + Courvoisier sign (palpable nontender gallbladder)
  • •Risk: smoking, chronic pancreatitis, age, family history, BRCA
  • •US first if unclear biliary obstruction; CT if high suspicion for pancreatic cancer
  • •Imaging: dilated CBD + pancreatic duct ('double duct sign')
  • •EUS with biopsy for tissue diagnosis
  • •CA 19-9 elevated (not diagnostic alone)
  • •Whipple if resectable; chemo if not

◆GIST

  • •Most common mesenchymal GI tumor
  • •From interstitial cells of Cajal
  • •CD117 (c-KIT) positive on biopsy
  • •Imatinib for metastatic; localized → surgical resection
  • •Size + mitotic index predict recurrence

◆Carcinoid syndrome

  • •Serotonin-secreting NET with hepatic mets
  • •Flushing, diarrhea, bronchospasm, right-heart valvular disease (TR, PS)
  • •24-hr urine 5-HIAA elevated
  • •Localize: CT, octreotide scan
  • •Treat: octreotide; surgical resection

◆Gastric adenocarcinoma

  • •Endoscopy + biopsy positive → CT abd/pelvis → PET/CT + EUS + CT chest + laparoscopy
  • •Limited stage: surgical resection ± perioperative chemo (FLOT)
  • •Advanced: systemic chemo ± immunotherapy + palliative

◆Gastrinoma (ZES)

  • •Multiple stomach ulcers + thickened gastric folds
  • •Stop PPI 1 week → check serum gastrin
  • •<110 = not gastrinoma; >1000 = check gastric pH off PPI; 110–1000 = secretin stimulation test (paradoxical rise >120 = positive)
  • •Localize: somatostatin receptor scintigraphy or EUS
  • •Surgical resection if possible; MEN-1 association
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