[Mucinous Cystadenocarcinoma with a Sarcomatous Component Arising from the Sigmoid Mesocolon-A Case Report].

A 53‒year‒old female was referred to our hospital for abdominal pain. A cystic tumor evolving since 12 years, which was suspected of being a lymphocyst, was detected in her left lower abdomen. Computed tomography(CT)revealed the cystic tumor with enhanced 80 mm enlarged regions. Regarding the laboratory data, inflammatory parameters and tumor markers such as CA19‒9, CEA, and CA125 were elevated. Mucinous cystadenocarcinoma was highly suspected and a surgery was performed. Laparotomy showed that the tumor was located in the sigmoid mesocolon and there were multiple peritoneal disseminations. The tumor could not be separated from the sigmoid colon; therefore, tumor resection with partial sigmoidectomy was performed. The resected specimens showed mucus and solid lesions in the cystic tumor. The pathological findings revealed that the cystic tumor from the sigmoid mesocolon was a mucinous cystadenocarcinoma with large spindle‒ shaped atypical cells, which were considered to have undergone sarcomatous changes. No cases of mucinous cystadenocarcinoma with sarcoma arising from the sigmoid mesocolon have been previously reported. The prognosis of mucinous cystic neoplasm with sarcoma is suspected to be very poor, and the accumulation of such cases could help in improving their treatment.

[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.

[Two Cases of Resectable Liver Metastasis from Colorectal Cancer with Pathological Complete Response after Neoadjuvant Chemotherapy].

A 57-year-old male, who had received a laparoscopic low anterior resection for rectal cancer 12 months ago, was diagnosed a resectable liver metastasis from rectal cancer by computed tomography(CT). Neoadjuvant chemotherapy with mFOLFOX6 plus bevacizumab and FOLFIRI plus bevacizumab was performed for liver metastasis. After neoadjuvant chemotherapy, partial response(PR)was proved on the Response Evaluation Criteria in Solid Tumors(RECIST)and partial resection of the liver was conducted. Pathological findings showed no viable cancer cells. He is alive without recurrence 5 years after the surgery. A 70-year-old female, who had received a laparoscopic high anterior resection for rectal cancer 17 months ago, was diagnosed a resectable liver metastasis from rectal cancer by CT. SOX plus bevacizumab was performed for liver metastasis. After neoadjuvant chemotherapy, PR was proved on the RECIST and right hepatic lobectomy was performed. Pathological findings showed no viable cancer cells and she is alive without recurrence 4 years after the surgery. We expected neoadjuvant chemotherapy for resectable liver metastasis might be an option of treatment.