From January 2010 to May 2018, a total of 2844 patients were diagnosed with GC at Haeundae Paik Hospital, Inje University, in Busan, Korea. Of these, 537 patients were excluded based on the following exclusion criteria: (i) patients who were diagnosed with other diseases such as gastrointestinal stromal tumor (GIST), carcinoid tumor, schwannoma, and leiomyosarcoma, and (ii) patients whose pathologic data were not available (n = 500). Among them, 88 (3.8%) and 2219 (96.2%) patients were ≤40 and >40 years of age, respectively.
To evaluate the long‐term follow‐up outcomes and compare patients younger and older than 40 years, we divided the patients into younger (≤40 years, n = 70) and older (>40 years, n = 70) age groups by propensity matching. We excluded eight patients meeting the following exclusion criteria: (i) no available clinical data or clinical records, (ii) gastric metastasis due to other primary‐originated cancer, and (iii) no pathological findings. In the propensity‐matching analysis, the covariates included gender and treatment modality. In summary, the propensity analysis included a total of 132 matched patients, including 70 younger and 62 older patients, diagnosed with GC between 2010 and 2018, who were included in further analyses of pathologic findings and outcomes (Fig. 1).
This study was conducted under the ethical guidelines of the 1975 Declaration of Helsinki and approved by the institutional review board of Haeundae Paik Hospital.