Neoplasia USMLE Step 1 Practice Question
A 61-year-old man with a 40-pack-year smoking history presents to the emergency department with progressive jaundice and right upper quadrant pain over 3 weeks. He reports unintentional weight loss of 8 kg over 2 months. Vital signs are stable. Laboratory studies show total bilirubin 7.1 mg/dL, direct bilirubin 6.4 mg/dL, alkaline phosphatase 287 U/L, and ALT 156 U/L. CT imaging reveals a 2.8-cm hypoattenuating mass in the pancreatic head with upstream pancreatic ductal dilation (5 mm to 8 mm) and intrahepatic biliary ductal dilation. Endoscopic ultrasound with fine-needle aspiration shows a ductal adenocarcinoma with marked stromal fibrosis comprising approximately 70% of the tumor volume. Which of the following best explains why this histopathologic feature is associated with this patient's poor prognosis?
Answer choices
- AThe desmoplastic stroma impairs drug delivery by creating a barrier that limits chemotherapy penetration into malignant epithelial cellsCorrect answer
- BThe extensive fibrosis provides mechanical support that prevents metastatic dissemination to distant organs
- CThe stromal fibrosis indicates the tumor has activated Wnt/β-catenin signaling, which typically responds well to targeted therapy
- DThe high stromal content reflects increased expression of E-cadherin, which preserves cellular differentiation and improves survival
- EThe extensive fibrotic reaction represents an attempt by the host immune system to wall off the tumor, reducing tumor growth rate
- FThe desmoplastic response is composed primarily of apoptotic tumor cells, indicating an immune-mediated tumor rejection response
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