Notes
Oncology
GI Cancer Screening & Management
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Oncology
GI Cancer Screening & Management
CRC screening, pancreatic CA, GIST, carcinoid.
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Colorectal cancer screening
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Average risk: start at 45 (USPSTF 2021, lowered from 50)
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Options: colonoscopy q10y, FIT annually, sigmoidoscopy q5y + FIT q3y, Cologuard (multi-target stool DNA) q3y
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FHx CRC in first-degree relative <60: start at 40 OR 10 years before relative's dx (whichever earlier); repeat q5 yr
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Lynch syndrome: colonoscopy q1–2y starting age 20–25
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Stop at age 75 if life-expectancy limited
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Symptomatic CRC
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Age >50 + weight loss + iron deficiency anemia + change in bowel habits = colonoscopy (NOT FOBT — that's screening)
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Confirmed CRC → CT abdomen/pelvis for staging
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Liver mets of unknown primary → consider colorectal source
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Pancreatic adenocarcinoma
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Painless jaundice + weight loss + pruritus + Courvoisier sign (palpable nontender gallbladder)
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Risk: smoking, chronic pancreatitis, age, family history, BRCA
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US first if unclear biliary obstruction; CT if high suspicion for pancreatic cancer
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Imaging: dilated CBD + pancreatic duct ('double duct sign')
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EUS with biopsy for tissue diagnosis
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CA 19-9 elevated (not diagnostic alone)
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Whipple if resectable; chemo if not
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GIST
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Most common mesenchymal GI tumor
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From interstitial cells of Cajal
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CD117 (c-KIT) positive on biopsy
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Imatinib for metastatic; localized → surgical resection
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Size + mitotic index predict recurrence
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Carcinoid syndrome
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Serotonin-secreting NET with hepatic mets
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Flushing, diarrhea, bronchospasm, right-heart valvular disease (TR, PS)
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24-hr urine 5-HIAA elevated
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Localize: CT, octreotide scan
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Treat: octreotide; surgical resection
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Gastric adenocarcinoma
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Endoscopy + biopsy positive → CT abd/pelvis → PET/CT + EUS + CT chest + laparoscopy
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Limited stage: surgical resection ± perioperative chemo (FLOT)
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Advanced: systemic chemo ± immunotherapy + palliative
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Gastrinoma (ZES)
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Multiple stomach ulcers + thickened gastric folds
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Stop PPI 1 week → check serum gastrin
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<110 = not gastrinoma; >1000 = check gastric pH off PPI; 110–1000 = secretin stimulation test (paradoxical rise >120 = positive)
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Localize: somatostatin receptor scintigraphy or EUS
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Surgical resection if possible; MEN-1 association
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