[Clinicopathological features and prognosis of early-onset gastric cancer: a large-scale retrospective real-world study].

To clarify the clinicopathological features, prognosis, and recurrence pattern of early-onset gastric cancer (EOGC). Using data from the gastric cancer database of Zhongshan Hospital, Fudan University, we performed a retrospective, large-scale, real-world study of 5046 patients with gastric cancer who had undergone redical or palliative gastrectomy from January 2013 to December 2018, including 425 patients with EOGC (age ≤45 years) and 4621 controls. All those patients were pathologically confirmed adenocarcinoma with complete follow-up of five years. Residue gastric cancer and patients without complete clinical or follow-up data were excluded. We used a combination of outpatient and telephone follow-up, ending in October 2022 (median duration of follow-up 60 months), and compared the clinicopathological features and prognosis of the two groups. The clinicopathological features of EOGC included female predominance (61.1% [262/425 vs. 26.3% [1217/4621], χ=234.215, <0.001), fewer comorbidities (31.3% [133/425] vs. 58.5% [2703/4621], χ=34.378, <0.001), poorer differentiation (90.6% [385/425] vs. 78.2% [3614/4621], χ=30.642, <0.001), higher proportion of diffuse type (53.9% [229/425] vs. 18.3% [846/4621], χ=274.474, <0.001), higher proportion of T4 stage (44.7% [190/425] vs. 37.5% [1733/4621], χ=17.535, =0.001), more lymph node metastases (60.5% [257/425] vs. 53.9% [2491/4621], χ=6.764, =0.009), and higher proportion of pathological stage III/IV (47.5% [202/425] vs. 42.4% [1959/4621], χ=4.093, =0.043). The 5-year overall survival rates of the EOGC and control groups were 55.1% and 49.1%, respectively. Overall survival was significantly better in the EOGC than in the control group (<0.001). According to subgroup analysis, the prognosis of pathological stage I/II/III EOGC was better than that of the control group. Recurrence rates were similar in the two groups, whereas patients with EOGC had a higher proportion of peritoneal recurrence (7.8% [33/425] vs. 3.2% [146/4621], χ=23.741, <0.001) and a lower proportion of distant metastasis (4.9% [21/425] vs. 8.3% [385/4621], χ=6.247, =0.012). EOGC has unique clinicopathological features and recurrence patterns and resectable EOGC has a better prognosis, suggesting that patients with EOGC should be actively treated with the focus on preventing peritoneal recurrence.