A 66-Year-Old Man With Gastric Carcinoma

Case: A 66-Year Old Male With HER2+ Gastric Cancer

Initial presentation

• A 66-year-old man complains of a 4-month history of decreased appetite and diffuse abdominal pain
• PMH: DM, medically controlled; colonoscopy at age 55 was unremarkable; no personal or family history of cancer
• PE: bloating; abdominal pain on deep palpation; otherwise unremarkable
  

Clinical Workup

• Labs: Hb 9.5 g/dL, plt 104 x 109/L; other lab values WNL
• Endoscopy with biopsy: showed well differentiated papillary adenocarcinoma with invasion into the lamina propria
• EUS: irregular borders on extraluminal surfaces with hyperechogenic spots
• Abdominal/pelvic CT confirmed a 5.1 cm lesion with indistinct margins in the antrum of the stomach
• Stage IV gastric adenocarcinoma; ECOG 1
• IHC score for HER2 expression 3+
• Biomarker testing: PD-L1 0%, NTRK -
• MSI by PCR/MMR by IHC: stable

Treatment

• He was started on FOLFOX + trastuzumab
  • Well tolerated for 5 cycles
  • Imaging showed 3 new small pulmonary lesions
• Treatment changed to docetaxel + ramucirumab
  • Treatment was well tolerated for 4 cycles when he developed neutropenia
• Patient was started on trastuzumab deruxtecan; repeat HER2 expression score was not indicated