This study is observational study to analyze the actual overall survival of the patients who did not receive adjuvant chemotherapy after curative gastrectomy for gastric cancer.

The investigators developed prediction model for the overall survival of these patients and validated.

Adjuvant chemotherapy (AC) after curative gastrectomy is the standard treatment for patients with locally advanced gastric adenocarcinoma in East Asia; however, for various reasons, some patients do not receive this treatment. The aim of this study was to develop a system that reflects the survival rate of patients without AC. A survival prediction model was developed based on the modified staging system and risk factors for overall survival (OS), which were examined using the Cox proportional hazards regression model. The model was validated for the power of prediction and discrimination, compared with the American Joint Committee on Cancer (AJCC) Cancer Staging Manual 8th edition; it was externally validated using an independent dataset. the newly developed survival prediction model improves the accuracy of OS prediction for stage II and III gastric cancer patients without AC after curative gastrectomy.

Inclusion Criteria:

• histologically confirmed primary gastric adenocarcinoma
• curative R0 resection with D2 lymph node dissection
• pathologic stage II or III gastric cancer

Exclusion Criteria:

• Patients who received neoadjuvant or AC treatment
• follow-up loss or death within 30 days of surgery
• completion of total gastrectomy
• other malignancy within 5 years before gastrectomy

Informed consent was not required because of the retrospective nature of the study. For the development set, the database of the Gastric cancer center at Seoul St. Mary's hospital was reviewed between January 2009 and December 2016. The inclusion criteria were: histologically confirmed primary gastric adenocarcinoma, curative R0 resection with D2 lymph node dissection, and pathologic stage II or III. Exclusion criteria were: neoadjuvant or AC treatment, follow-up loss or death within 30 days of surgery, completion of total gastrectomy, and other malignancy within 5 years before gastrectomy. Finally, 185 patients with locally advanced GC, all of whom underwent curative gastrectomy without chemotherapy, were included in the development set. The validation set consisted of patients who satisfied the above inclusion and exclusion criteria from St. Vincent's hospital in the same period. Finally, 157 patients were included in the validation set

The data that support the findings of this study are available from the corresponding author upon reasonable request.

January 2022, 3 years