A real-world study on epidemiology, biomarker test results, clinical characteristics, and treatment patterns of unresectable locally advanced or metastatic gastric and gastroesophageal junction adenocarcinoma in China.

e16013 Background: Gastric cancer is the fifth most common cancer and third leading cause of cancer-related death in China, with about 90% classified as adenocarcinoma. Many patients (pts) also have gastroesophageal junction adenocarcinoma (GEJa). For most pts, diagnosis often occurs at an advanced stage. The aim of this observational, descriptive study was to understand the epidemiology, biomarker test results, clinical characteristics, and treatment patterns of unresectable locally advanced or metastatic (la/m) gastric adenocarcinoma (Ga) and GEJa in China. Methods: Electronic medical records dated January 2015–December 2022 from the China National Cancer Center Oncology Information Database were used. Eligible adults were diagnosed with la/m Ga and GEJa between January 2016 and June 2022. Demographic or clinical characteristics were assessed at index date (first diagnosis of la/m Ga or GEJa) or during the baseline (BL) period (1 year prior to and inclusive of index date). Biomarker test results were collected at BL and during the follow-up (f/u) period (until last hospital visit, occurrence of other primary cancer, participation in a clinical trial, or study termination, whichever came first). Treatments at f/u were also described. Results: From 2016–2022, 189,725 and 60,878 pts were diagnosed with Ga and GEJa, respectively, including 64,807 (34.2%) and 18,412 (30.2%) with late-stage (la/m) disease. A total of 22,156 la/m Ga pts and 6183 la/m GEJa pts met study criteria and are described henceforth; 67.0% and 82.9%, respectively, were male, and mean (SD) age at diagnosis of la/m disease was 59.0 (12.3) and 64.5 (10.1) years. Of pts with HER2 biomarker test results at BL, 309/3348 (9.2%) la/m Ga pts and 142/1087 (13.1%) la/m GEJa pts were HER2-positive (per IHC 2+/3+ or FISH); of pts with ≥1 HER2 test result at f/u, 895/7388 (12.1%) la/m Ga pts and 373/2162 (17.3%) la/m GEJa pts were HER2-positive. Of pts with PD-L1 combined positive score (CPS) test results at BL, 176/385 (45.7%) la/m Ga pts and 64/149 (43.0%) la/m GEJa pts had CPS ≥5; of pts with ≥1 PD-L1 CPS test result at f/u, 727/1539 (47.2%) la/m Ga pts and 229/513 (44.6%) la/m GEJa pts had CPS ≥5. First- (1L) and second-line (2L) treatments were recorded for a subset of pts. Oxaliplatin + tegafur was the most common 1L treatment, received by 3431/14,386 (23.8%) la/m Ga pts (median treatment duration: 2.9 mo [IQR: 1.4–5.6]) and 921/4335 (21.2%) la/m GEJa pts (2.8 mo [IQR: 1.4–5.4]). Chemotherapy with an anti-VEGF drug (apatinib) was the most common 2L treatment, received by 795/5495 (14.5%) la/m Ga pts (median treatment duration: 1.8 mo [IQR: 1.0–3.5]) and 276/1827 (15.1%) la/m GEJa pts (2.2 mo [IQR: 1.2–3.9]). Conclusions: Treatment patterns suggest an ongoing need to improve the care of la/m Ga and GEJa in China.