Clinicopathologic characteristics, survival, and treatments for gastric adenosquamous carcinoma: a population-based study

Clinicopathological significance of deficient DNA mismatch repair and MLH1 promoter methylation in gastric adenosquamous carcinoma

Primary gastric adenosquamous carcinoma (GASC) is a rare tumor that exhibits aggressive behavior and currently lacks standardized therapeutic recommendations. Microsatellite instability (MSI)/mismatch repair deficiency (dMMR) and positive PD-L1 expression confer sensitivity to immune checkpoint inhibitors; however, their statuses in GASC remain uncertain. In this study, clinical features, MMR/MSI status, MLH1 methylation, two T-cell markers, and PD-L1 expression of 30 GASC cases were collected from three institutions. Additionally, 196 gastric adenocarcinomas (GACs) were collected for comparison. The median age of GASC patients was 62 years, with 76.7% being males, and 56.7% at stage III. dMMR/MSI-high with MLH1 hypermethylation was observed in 33.3% GASCs, and was significantly associated with older age, female, distal location, larger size, deeper tumor invasion, and higher CD3 and CD8 densities and PD-L1 expression. Both glandular and squamous components of all dMMR GASCs showed loss of MLH1 and PMS2 expression. No significant difference in overall survival was observed between dMMR and mismatch repair proficiency (pMMR) GASC patients, while inferior overall survival was observed in pMMR GASC treated with surgery alone compared to those receiving chemotherapy. When comparing to GAC, GASC exhibited clinicopathological features indicative of more aggressive behavior (larger size, poorly tumor differentiation, deeper tumor invasion and more lymph node metastases). A significantly higher frequency of dMMR was found in GASC (33.3%) than that in GAC (16.3%). This study offers a comprehensive perspective on the clinicopathological features of GASC, emphasizing a subset of GASC associated with dMMR and MLH1 hypermethylation. Immunotherapy might be a promising strategy for GASC.

Mixed Pancreatobiliary Ductal Adenocarcinoma and Squamous Cell Carcinoma Arising from an Ectopic Pancreas in a Gastric Duplication Cyst-A Rare Double Diagnosis

Gastric duplication cysts (GDCs) are rare congenital anomalies, often identified during infancy or childhood. Although typically benign, there have been sporadic reports of malignant transformations, including adenocarcinoma and rare mixed tumors. Herein, we describe a rare case of mixed pancreatobiliary ductal adenocarcinoma and squamous cell carcinoma occurring within a GDC in a 54-year-old Korean woman with a history of melena and hematemesis. Initial gastroscopy and positron emission tomography-computed tomography (PET-CT) revealed a protruding stomach mass. A laparoscopic total gastrectomy was performed, and histological examination confirmed a mixed carcinoma originating from an ectopic pancreas within the duplication cyst. This case is unique as it is the first reported instance in the world of mixed pancreatobiliary ductal adenocarcinoma and squamous cell carcinoma arising from an ectopic pancreas within a GDC. This highlights the importance of considering pancreatobiliary-type adenocarcinoma in the differential diagnosis of malignancies originating from GDCs, which has implications for treatment strategies.

Analysis of clinicopathological characteristics and prognosis on primary gastric adenosquamous carcinoma

Primary gastric adenosquamous carcinoma (PGASC) is a rare type of gastric cancer with limited research and poorly understood clinicopathological features. This study investigated the clinicopathological features and outcomes of PGASC. Patients with PGASC from Union Hospital, Tongji Medical College, Huazhong University of Science and Technology and from the published literature were enrolled in this study. Survival curves were generated using the Kaplan-Meier method, and prognostic factors were identified through Cox proportional hazards regression models. This study identified 76 eligible cases of PGASC, with 45 cases from published literature and 31 from our center. The most prevalent symptoms were abdominal pain and dysphagia, with a median age of 62 years (range: 29-84 years). The primary lesions were predominantly in the proximal stomach, with a median tumor size of 6.5 cm (range: 1.5-16.0 cm). Tumor stages II, III, and IV were detected in 12 (16.7%), 43 (59.7%), and 17 (23.6%) patients, respectively. Most tumors were poorly differentiated in both the squamous cell carcinoma (SCC) component and adenocarcinoma (AC) component. The median survival time was 17 months (range: 2-122 months). The 1, 3, and 5-year overall survival (OS) was 60.7%, 31.1%, and 24.1%, respectively. Multivariate analysis revealed that OS was independently predicted by the proportion of SCC component, differentiation of AC component, and tumor stage. PGASC is a rare disease with a poor prognosis. A high proportion of SCC components, low differentiated AC components, and advanced tumor were associated with worse survival in patients with PGASC. Adjuvant therapy did not improve survival time.

Immunoprofile of adenosquamous carcinoma in gastric cancer

BACKGROUND

Gastric adenosquamous carcinoma (GASC) is a rare subtype of gastric cancer. Research on GASC treatment is limited, and its outcome is usually poor. We investigated the clinical features, immunoprofile of GASC, and determined the optimal treatment modality for these patients.

METHODS

Patients with GASC from Taipei Veterans General Hospital were retrospectively reviewed. Clinical features and treatment outcomes were evaluated. Adequate samples were examined for surrogate biomarkers for immunotherapy by IHC staining.

RESULTS

Total 14 (0.35%) GASC patients were found among 4034 gastric cancer patients. The median tumor size was 6.8 cm in 10 patients with stage III GASC, and all these patients underwent radical gastrectomy followed by adjuvant therapy. The median progression-free survival (PFS) and overall survival (OS) were 6.0 and 11.5 months, respectively. Two patients with stage IV GASC received frontline immunotherapy. Their median PFS and OS were 9.0 and 12.5 months. In immunoprofiling, 25.0% (n = 3), 75.0% (n = 9), and 33.3% (n = 4) of the samples had deficient mismatch repair (dMMR) protein, combined positive score (CPS) of ≥1, and CPS of ≥10, respectively. The univariate analysis revealed that programmed death-ligand 1 ≥5% (HR: 0.12; 95% CI: 0.01-0.97; p = 0.047) was significant associated with superior OS. One stage IV patient with CPS ≥10 and dMMR proteins received nivolumab monotherapy as frontline treatment that resulted 14-month PFS.

CONCLUSION

Patients with GASC are more likely to yield positive results for CPS and dMMR. Biomarkers should be examined, and immunotherapy can be considered as frontline systemic treatment.

Epstein-Barr virus-associated gastric adenosquamous carcinoma with concurrent gastric carcinoma with lymphoid stroma: a case report and review of the literature

BACKGROUND

Adenosquamous carcinoma (ASC)with concurrent gastric carcinoma with lymphoid stroma (GCLS) are extremely rare tumors. There are only limited cases reported in the literature. Epstein-Barr virus (EBV) infection was found in the concomitant GCLS, but none in the ASC. Here, we report the first case of gastric cancer with EBV infection detected in both ASC and GCLS.

CASE PRESENTATION

A 59-year-old man complained of intermittent upper abdominal pain. The gastric endoscopy revealed a type IIc tumor located in the gastric body near the fundus of the stomach. Histological examination of the gastric tumor showed the coexistence of ASC and GCLS. Both components were positive for EBV-encoded RNA (EBER) in situ hybridization. Neoplastic nests of the former were positive for p63, p40 and CK5/6. The glandular components showed positive acid mucus in the Alcian-blue periodic-acid-schiff (AB-PAS) staining. There was significant difference in the expression of epidermal growth factor receptor (EGFR) between adenocarcinoma and squamous carcinoma, but not in other proteins such as human epidermal growth factor receptor 2 (HER2), p53 and mismatch repair proteins. The role of EGFR signaling pathway needs to be further explored in the differentiation of squamous carcinoma in the gastric ASC. Finally, a diagnosis of early EBV associated gastric ASC with concurrent GCLS (pT1bN1) was made. The patient took a single-drug S1 periodically for half a year after the surgery and has been disease free during 8 months of medical follow-up.

CONCLUSIONS

This is the first case of EBV associated gastric ASC with concurrent GCLS, and pathologists and clinicians should recognize and pay attention to this type of tumor.