[A Case of HER2 Positive Gastric Cancer That Was Highly Responsive to Fifth-Line Chemotherapy with Trastuzumab].

A 76-year-old male underwent distal gastrectomy for gastric cancer and pathological findings showed Stage Ⅳ(T4a, N3a, M1, H0, P0, CY1)with HER2 positivity. He received chemotherapy with S-1 and oxaliplatin(SOX)plus trastuzumab and no disease progression was shown. However, because of Grade 3 adverse skin effects to S-1, he could not continue with the regimen. He switched to a regimen of ramucirumab plus paclitaxel, followed by nivolumab, and later irinotecan. However, the disease progressed and multiple lung metastases as well as a left adrenal metastasis appeared. Fifth-line chemotherapy with trastuzumab was administered. After 4 courses, the lung metastases reduced and the left adrenal metastasis shrank from 46 mm to 33 mm. These results were consistent with a partial response on the Response Evaluation Criteria in Solid Tumors. In addition, CEA and CA19-9 also decreased significantly. Unfortunately, after 10 courses, the patient's disease progressed.

[Two Cases of Locally Advanced Colorectal Cancer Involving Pathological Complete Response after Chemotherapy].

We report 2 cases of locally advanced colorectal cancer in which complete response(CR)was achieved after chemotherapy. Case 1 involved a 71-year-old male diagnosed with rectal cancer invading the bladder. Chemotherapy with SOX plus bevacizumab and IRIS plus bevacizumab was administered for rectal cancer. Post-chemotherapy, the disease showed clinical CR(cCR)according to the Response Evaluation Criteria in Solid Tumors(RECIST). A laparoscopic abdominoperineal resection was then performed, with pathological findings showing no viable cancer cells. Eleven months postoperatively, the patient remains alive without disease recurrence. Case 2 involved a 54-year-old female diagnosed with a peritoneal abscess resulting from perforated sigmoid colon cancer. She received chemotherapy with SOX plus bevacizumab. Post-chemotherapy, the disease showed cCR according to the RECIST. A sigmoidectomy was performed, with pathological findings showing no viable cancer cells. Ten months postoperatively, the patient remains alive without disease recurrence. We believe that neoadjuvant chemotherapy is a feasible treatment option for locally advanced colorectal cancer.