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

Table 1 Prevalence and features of synchronous gastric neoplasms detected endoscopically

Ref.	Country	Study design	Setting and number of patients	Frequency and type of SGN, n (%)	Characteristics of synchronous neoplasm
Asonuma et al[10], 2024	Japan	Prospective multicenter	Patients undergoing ESD, 802	130 (16.2), EGC	Males: 81.5%
Shin et al[20], 2020	South Korea	Retrospective	Patients undergoing ESD/EMR, 1569	182 (11.6), cancer, adenoma	Age: 66.1 ± 8.0 years; males: 75.8%; location: Lower third 61.5%, middle third 34.6%, upper third 3.9%
Lim et al[19], 2015	South Korea	Retrospective	Patients undergoing ESD/EMR, 971	56 (5.8), EGC, HGD	Age: 64.5 (7.8) years; males: 78.6%. Location: Lower third 67.9%, middle third 28.6%, upper third 3.6%. Undifferentiated 7.1%
Gweon et al[14], 2015	South Korea	Retrospective	Patients undergoing EMR/ESD, 678	41 (6), cancer, dysplasia	Location: Upper third 7.3%, middle third 36.6%, lower third 56.1%. Morphology: Elevated 51.3%, flat 34.1%, depressed 14.6%
Park et al[15], 2014	South Korea	Retrospective	Patients undergoing ESD/EMR, 228	46 (20.1), EGC, HGD, LGD	Age: 66.1 ± 7.1 years; males: 71.7%. Morphology: Elevated 87%, protruding 8.7%, flat depressed 4.3%. Location: Lower third 61.4%, middle third 35.1%. Undifferentiated 2.2%
Kim et al[18], 2013	South Korea	Retrospective	Patients undergoing ESD, 602	38 (6.3), cancer, adenoma
Kim et al[9], 2013	South Korea	Retrospective multicenter	Patients undergoing ESD, 3018	275 (9.1), cancer, adenoma	Age: 67.4 years; males: 73.8%. Morphology: Elevated 53.1%, depressed 37.8%
Jang et al[17], 2013	South Korea	Retrospective	Patients who underwent ESD/EMR, 512	66 (12.9), EGC, adenoma
Kato et al[8], 2013	Japan	Retrospective multicenter	Patients who underwent ESD, 1258	110 (8.7)
Kasuga et al[7], 2013	Japan	Retrospective	Patients undergoing ESD, 851	62 (7.3), EGC	Age: 70.6 years; males: 71%. Location: Upper third 20%, middle third 40%, lower third 40%. Differentiated 96.8%

ESD: Endoscopic submucosal dissection; EMR: Endoscopic mucosal resection; EGC: Early gastric cancer; HGD: High-grade dysplasia; LGD: Low-grade dysplasia; SGN: Synchronous gastric neoplasm.

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.

Table 3 Risk factors for synchronous gastric neoplasms

Ref.	Older age	Male gender	Well differentiated PN	Lower stage of PN	AG/IM in background mucosa
Zhao et al[32], 2020					1
Zhu et al[33], 2020		1			1
Isobe et al[11], 2013	1	1
Jang et al[17], 2013	1
Lee et al[27], 2012		1	1		1
Fujita et al[44], 2010	1		1
Ribeiro et al[28], 2007			1	1
Otsuji et al[13], 2005	1		1	1
Arai et al[34], 2004	1	1	1
Lee et al[35], 2001	1	1		1
Takeshita et al[30], 1997	1	1	1
Seto et al[29], 1996	1	1	1
Kodama et al[25], 1996	1		1
Kosaka et al[26], 1990	1	1	1

1: Represent a positive relationship of the factor with synchronous gastric neoplasm; PN: Primary neoplasm; AG: Atrophic gastritis; IM: Intestinal metaplasia.