[A case of HER2-positive advanced gastric cancer with extensive lymph node metastasis treated via chemotherapy with a trastuzumab-containing regimen followed by conversion surgery].

A 62-year-old man presented with type 3 gastric cancer (tub1, HER2 positive) in the cardia, with 10-cm direct invasion into the lower esophagus, and extensive lymph node metastasis (Virchow and paraaortic nodes). Trastuzumab (Her), in the XP regimen (capecitabine and cisplatin [CDDP] plus Her; Xeloda®: 2,000 mg/m² on day 1-14, CDDP: 80 mg/m² on day 1, Her: 8(6) mg/kg on day 1), was administered every 3 weeks and repeated for 6 courses. After administering 6 courses of the XP plus Her regimen, without severe adverse events in the patient, computed tomography (CT) revealed shrinkage of both the main tumor and the metastatic sites, by 51%. Esophagectomy and proximal gastrectomy with 3-field lymphadenectomy and gastric tube reconstruction was performed via right thoracotomy and laparotomy (R0). However, Grade 3 pneumonia occurred postoperatively, and the patient was discharged on day 67 after surgery. After treatment, the tumor was histologically evaluated as Grade 1b gastric cancer, and remnant cancer cells also expressed HER2. The patient was too frail to receive adjuvant chemotherapy, and he died of pneumonia 11 months after surgery, without obvious relapse. Perioperative chemotherapy with a regimen containing Her has a possible role in treating advanced HER2-positive gastric cancer. Multiple invasive conversion surgeries might decrease the feasibility of adjuvant chemotherapy and worsen the prognosis.