Clinicopathological Features and Outcomes of SMARCA4-Deficient Carcinomas of the Stomach and Gastroesophageal Junction: A Case Series and Literature Review

There are relatively few reports on SMARCA4-deficient gastric cancer, which is a highly aggressive tumor. Most patients are already at an advanced stage at the time of diagnosis. In this study, we identify the absence of SMARCA4 staining in the stomach tumors from four adult male patients and one female patient between the ages of 61 and 78 years. Surgical resection was performed in four patients (specimens 1 to 4), who presented with ulcerated and transmural masses with infiltration, which were staged as IIIA in specimens 1 and 4, IIB in specimen 2, and IIIC in specimen 3. Histologically, the tumor cells were arranged in sheets, nests, cords or trabecular patterns in five specimens, while specimen 2 also included the adenocarcinoma component, which consisted of a low-grade gland-forming adenocarcinoma. Immunohistochemical staining revealed deficient SMARCA4 expression in five specimens, but expressed SMARCA4 in the adenocarcinoma component in specimen 2. Patients 1 and 2 received postoperative chemotherapy, with no evidence of disease recurrence to date. Patient 5 presented with liver metastases and was managed with immunotherapy plus chemoradiation (nonsurgical approach), and survived with persistent disease for 10 months. We analyze the clinicopathological features, immunohistochemical characteristics, therapy and prognosis of stomach and gastroesophageal junction SMARCA4-deficient carcinomas and presented a literature review to aid in the diagnosis and differential diagnosis of these tumors.