AbstractObjectiveThe objective of this study is to explore the clinicopathological characteristics of gastric cancer and precancerous conditions in patients with primary gastric lymphoma.MethodsWe analyzed 474 cases of primary gastric lymphoma, mainly DLBCL and MALT, from three clinical centres retrospectively, and compared the clinicopathological parameters of primary gastric lymphoma patients complicated with gastric cancer, precancerous conditions, or with no complications.ResultsA total of 5.1% of the patients with primary gastric lymphoma were diagnosed with gastric cancer, including metachronous gastric adenocarcinoma (3.2%) and synchronous gastric adenocarcinoma (1.9%). Of the patients with gastric lymphoma, 14.6% had precancerous conditions including atrophy (14.6%), intestinal metaplasia (8.9%), and low-grade intraepithelial neoplasia (1.9%). Primary gastric lymphoma patients with an ulcerative type (p= 0.009) and Lugano classification stage IIE + IV (p< 0.001) lymphoma had a higher risk of complicating with gastric cancers or precancerous conditions. The rate of infection ofHelicobacter pylori(Hp) was 68.4% in patients with primary gastric lymphoma, which was higher in patients with MALT lymphoma (p< 0.001), Lugano classification stage I + II (p< 0.001), and patients complicated with precancerous conditions and gastric cancer (p< 0.001), especially gastric cancer of the intestinal type (p= 0.04). Gastric cancer (95.8%) and precancerous conditions (91.3%) occurred mostly in Hp-infected primary gastric lymphoma patients, with a minor subset of Hp-eradicated patients. Primary gastric lymphoma patients had a higher detection rate of early gastric cancer (25.0%) and a five-year survival rate (40.0%) than the general Chinese population.ConclusionsPatients with primary gastric lymphoma have a high risk of developing gastric cancer and precancerous conditions, and this risk may be related toHelicobacter pyloriinfection. Follow-up of primary gastric lymphoma provides an opportunity for the detection of early gastric cancer.Key messages5.1% of the patients with primary gastric lymphoma were diagnosed with gastric cancer.14.6% of the patients with gastric lymphoma had premalignant lesions including atrophy (14.6%), intestinal metaplasia (8.9%), and low-grade intraepithelial neoplasia (1.9%).Primary gastric lymphoma patients complicating with gastric cancer had a higher infection rate ofHelicobacter pylori(100.0%), a detection rate of early gastric cancer (25.0%) and a five-year survival rate (40.0%) than the general Chinese population.