A 51-year-old man presented with an abnormal gastric shape on medical examination. Esophagogastroduodenoscopy revealed type 1 tumor of the esophagogastric junction (Fig. 1a, b). Pathological examination of the biopsied specimens showed a moderately tubular adenocarcinoma with mucinous adenocarcinoma. Abdominal computed tomography (CT) did not indicate swelling of any lymph node or distant metastasis. On the basis of these clinical and pathological findings, we diagnosed the patient with Siewert type II esophagogastric junction adenocarcinoma (T2 N0 M0 stage IB). Although we initially performed proximal gastrectomy in January 2009, we soon converted to total gastrectomy with D2 lymphadenectomy due to the intrasurgical detection of a lymph node metastasis in station no. 2. The resected specimen showed tumor measuring 25 × 17 mm (Fig. 2), and the tumor was identified as mucinous adenocarcinoma on the basis of histological classification (Fig. 3a, b). According to the pathological examination of resected specimens, his tumor was T1b N1 M0 stage IB and HER2 status was negative. He was followed up every 2 to 3 months without adjuvant chemotherapy by regular clinical diagnostic examinations, such as tumor marker studies (CEA and CA19-9) and computed tomography.
In June 2009, CT showed an isolated small nodule measuring 3 mm in the right lower lobe of the lung. Because the lesion exhibited normal uptake on fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET), the patient was followed up with close observation only.
In June 2010, CT indicated that the lung nodule had increased to 8 mm in size (Fig. 4). We partially resected the right lower lung, including the nodule. Since pathological examination showed the resected lung tumor was a mucinous adenocarcinoma with positive expression of cytokeratin (CK) 7 and negative expression of CK 20, thyroid transcription factor-1, and apoprotein A, it was judged as a distant metastasis from the esophagogastric junction adenocarcinoma. HER2 status in lung metastatic lesion was not explored due to primary tumor with HER2 negative.
After lung resection, he received adjuvant chemotherapy with S-1. The treatment schedule was the oral administration of S-1 (120 mg/body) for 4 weeks, followed by 2 weeks of rest, repeated every 6 weeks. This adjuvant chemotherapy with S-1 was continued for 1 year. Although a May 2013 CT showed swelling of the upper mediastinal lymph node, the maximum standardized uptake value (SUVmax) in FDG-PET was 2.3. Consequently, he was followed up by observation. In September 2014, FDG-PET indicated that this node now demonstrated increased FDG uptake (SUVmax, 2.8) (Fig. 5). The lymph node specimens obtained by ultrasonography-guided needle biopsy appeared to be mucinous adenocarcinoma, identical to this patient’s esophagogastric junction cancer. He was enrolled in a clinical trial and received five courses of trastuzumab in combination with capecitabine and cisplatin. The therapeutic schedule included the oral administration of capecitabine (3000 mg/body) for 2 weeks, followed by 1 week of rest, repeated every 3 weeks, and administration of both cisplatin (80 mg/m2) and trastuzumab (8 mg/kg in the first course and 6 mg/kg after second courses) on day 1.
Following chemotherapy, CT showed decreased size of the metastatic lymph node. In April 2015, he underwent left upper mediastinal lymphadenectomy by the left cervical approach. Mucinous adenocarcinoma was identified by pathological examination. Although we proposed chemoradiotherapy after surgery, he refused our suggestion. Accordingly, he underwent radiation therapy with a total of 50.4 Gy introduced into the upper mediastinal field. In September 2015, he was treated with the oral administration of S-1 (80 mg/body) for 2 weeks, followed by 2 weeks of rest, repeated every 4 weeks. Since he could not continue chemotherapy because of grade 2 neutropenia and grade 1 fatigue, we stopped chemotherapy after only two courses. At 8 years and 4 months after the initial surgery, this patient exhibited no signs of disease recurrence on follow-up examinations.