# Proportional Frequency and Clinical Characteristics of Gastric, Esophageal, and Gastroesophageal Junction Cancers in a Private Medical Group in Brazil

## TL;DR

This study analyzed the frequency and characteristics of gastric, esophageal, and gastroesophageal junction cancers in Brazil, highlighting low biomarker testing rates.

## Contribution

The study provides new insights into the proportional frequency and clinicopathological features of GEJC in Brazil, emphasizing diagnostic and treatment gaps.

## Key findings

- GEJC accounted for 12.2% of cases, with a GEJC to GC ratio of 0.190.
- Biomarker testing rates were extremely low, with only 7.1% of GC cases testing for HER2.
- Most GC and GEJC cases were of the intestinal subtype, and EC was predominantly adenocarcinoma.

## Abstract

Gastric cancer (GC) and esophageal cancer (EC) are among the most prevalent malignancies globally and are leading causes of cancer-related mortality. Gastroesophageal junction cancer (GEJC) is considered a distinct entity with specific histopathological characteristics. This study aimed to determine the proportional frequency of GEJC; the clinicopathological characteristics of GC, EC, and GEJC; and adherence to clinical diagnostic guidelines using data from a large private healthcare network in Brazil.

In this retrospective, cross-sectional, descriptive study and database review, records from a Brazilian medical group (Dasa) were evaluated for adults (aged ≥ 18 years) who underwent upper digestive endoscopy between July 1, 2019, and June 30, 2022. Test results from the biopsy date associated with GC, EC, or GEJC diagnosis through December 2022 were collected retrospectively.

In total, 181 patients were evaluated, including 116 (64.1%) with GC, 37 (20.4%) with EC, 22 (12.2%) with GEJC, and six (3.3%) with lesions in ≥ 2 locations of interest. The ratio of GEJC to GC cases was 0.190, and the ratio of GEJC to EC cases was 0.595. Median (interquartile range) age at diagnosis was 67 (60 - 76) years, and most patients (57.5%) were aged 60 - 79 years. Sixty-two (53.4%), 27 (73.0%), 17 (77.3%), and four (66.7%) patients with GC, EC, GEJC, and lesions in ≥ 2 locations of interest, respectively, were male. The most frequently observed Lauren subtype was intestinal type for both GC and GEJC (68 (58.6%) patients and 18 (81.8%) patients, respectively). Adenocarcinoma was the most frequent histologic subtype observed in patients with EC (n = 21; 56.8%). Among patients with GC, EC, or GEJC and immunohistochemical biomarker testing, human epidermal growth factor receptor 2 expression was positive in 2/28 (7.1%), 1/3 (33.3%), and 1/2 (50.0%) patients, respectively, and mismatch repair deficiency was detected in 2/28 (7.1%), 0/3 (0%), and 0/2 (0%) patients. No patients with GEJC were tested for programmed cell death ligand 1 or claudin 18.2.

An improved understanding of GEJC characteristics in Brazil is essential for facilitating early diagnosis, identifying optimal treatment strategies, and informing public health policies. The extremely low rates of biomarker testing in this study revealed a significant gap in the implementation of modern oncology guidelines.