Frequency and characteristics of synchronous gastric cancers: Need for improved awareness and better detection

Table 2 Prevalence and features of synchronous gastric neoplasms detected on surgically resected specimens

Ref.	Country	Study design	Setting and number of patients	Frequency and type of SGN, n (%)	Characteristics of synchronous neoplasm
Zhao et al[32], 2020	China	Retrospective	Gastric cancer, 364	26 (7.1)	Age > 60 years: 53.8%. Males: 73.1%. Location: Lower third 76.9%, middle third 19.2%, upper third 3.8%. Morphology: Elevated/flat: 23.8%, depressed: 76.9%. Differentiated: 26.9%. Undifferentiated: 73.1%
Zhu et al[33], 2020	China	Retrospective	Early gastric cancer, HGIN, 644	44 (6.8)
Lin et al[12], 2019	China	Retrospective	Gastric cancer, 4107	133 (3.2)
Isobe et al[11], 2013	Japan	Retrospective	Early gastric cancer, 1340	146 (10.9)	Age: 68 years. Males: 81.5%. Differentiated: 80.8%
Kim et al[24], 2012	South Korea	Retrospective	Gastric cancer, 3320	188 (5.7)	Age: 57.5 ± 10.7 years. Males: 71.8%
Lee et al[27], 2012	South Korea	Retrospective	Early gastric cancer, 2299	117 (5.1)	Age: 56.5 years. Male: 63%. Location: Upper third 10.3%, middle third 20.3%, lower third 69.1%. Morphology: Elevated 14.3%, flat 26.3%, depressed 50.9%, others 9%. Well differentiated: 42.1%. Poorly differentiated: 57.9%
Lee et al[16], 2010	South Korea	Retrospective	Surgery, ESD/EMR for gastric neoplastic lesions, 986	51 (5.17)	Age: 63.25 ± 8.11 years. Males: 84.3%
Fujita et al[22], 2009	Japan	Retrospective	Gastric cancer, 2120	153 (7.2)	Age: 63.2 years. Males: 71.4%. Location: Upper third 6.5%, middle third 51%, lower third 42.5%. Differentiated: 59.4%
Ribeiro et al[28], 2007	Brazil	Retrospective	Gastric cancer, 553	19 (3.43)	Age: 66.8 years. Males: 68.4%
Otsuji et al[13], 2005	Japan	Retrospective	Gastric cancer, 1481	76 (5.1)	Age: 63.1 years. Male: 74%. Location: Upper third 17%, middle third 42%, lower third 41%
Borie et al[21], 2003	France	Retrospective multicenter	Early gastric cancer, 333	33 (9.9)	Males: 51.5%. Morphology: Elevated 21.2%, depressed 66.7%, flat 12.1%. Location: Upper third 15.2%, middle third 30.3%, lower third 54.5%. Differentiated: 54.5%. Undifferentiated 45.5%
Wittekind et al[31], 1997	Germany	Retrospective	Gastric cancer, 1664	61 (3.7)	Age: 67.7 years. Males: 69%
Takeshita et al[30], 1997	Japan	Retrospective	Early gastric cancer, 521	61(11.7)	Age: 64 years. Males: 78.7%. Differentiated: 64%
Seto et al[29], 1996	Japan	Retrospective	Gastric cancer, 911	82 (9)	Age: 61.3 years. Male: 81.7%. Location: Upper third 4.1%, middle third 49.5%, lower third 46.4%. Morphology: Elevated 33%, depressed 67%. Differentiated: 83%. Undifferentiated: 17%
Kodama et al[25], 1996	Japan	Retrospective	Gastric cancer, 1563	107 (6.8)	Age > 49 years: 84.1%. Males: 74.8%. Morphology: Elevated 31.8%. Differentiated 38.9%
Kaibara et al[23], 1993	Japan	Retrospective	Gastric cancer, 1606	132 (8.2)
Kosaka et al[26], 1990	Japan	Retrospective	Gastric cancer, 852	49 (5.8)

SGN: Synchronous gastric neoplasm; HGIN: High grade intraepithelial neoplasia; ESD: Endoscopic submucosal dissection; EMR: Endoscopic mucosal resection.