Systematic review of D2 lymphadenectomy versus D2 with para-aortic nodal dissection for advanced gastric cancer

Table 1 Characteristics of included studies (ITT: intention-to-treat)

Study ID (author, yr)	Design	Methods	Patients	Interventions	Outcomes	Notes
Jiang et al 2000[36]	RCT	Single center, parallel group, not clear about the method of randomization	Histologically proved curable advanced gastric cancer	D2 vs D2+	Post-operative morbidity and mortality; Operation time	Regional lymph nodes were classified according to 1th English edition 1995[32]
Sano et al 2004[37] and Sasako et al 2008[39] Kodera et al 2005[38]	RCT	Multicenter, parallel group, computer stratified randomization	Histologically proved advanced and curable gastric cancer	D2 vs D2+	Post-operative morbidity and mortality; Operation time; Blood loss during operation; Five-year survival rate	ITT was used in result analysis; Regional lymph nodes were classified according to 1th English edition 1995[32]
Yonemura et al 2006 and 2008[40,41]	RCT	Multicenter, parallel group, computer randomization	Younger than 75-yr old, histologically proved advanced and curable gastric cancer	D2 vs D2+	Post-operative morbidity and mortality; Operation time; Blood loss during operation; Five-year survival rate	Sample size was calculated before trials
Kulig et al 2007[42]	RCT	Multicenter, parallel group, simple computer randomization.	Histologically proved curable gastric adenocarcinoma	D2 vs D2+	Post-operative morbidity and mortality; Operation time; Blood loss during operation	Regional lymph nodes were classified according to 2nd English edition 1998[31]; ITT was used in result analysis
Maeta et al 1999[43]	non-RCT	Single center, parallel group, without randomization	Histologically proved advanced gastric cancer, younger than 75-yr old	D2 vs D2+	Post-operative morbidity and mortality; Operation time; Blood loss during operation	In D4 group, lymph nodes (a1, a2, b1 and b2) were all removed; Sample size was smaller than that calculated before study
Bostanci et al 2004[44]	non-RCT	Single center, parallel group, prospective study without randomization	Histologically proved gastric cancer	D2 vs D2+	Post-operative morbidity and mortality; Operation time	Surgical procedure was not very clearly described in the article
Kunisaki et al 2006[45]	non-RCT	Multicenter, parallel group, retrospective analysis	Curable advanced gastric cancer proved by histology	D2 vs D2+	Post-operative morbidity and mortality; Operation time; Blood loss during operation; Five-year survival rate	Data about length of post-operative hospital stay were obtained from the author
Hu et al 2009[46]	non-RCT	Single center, parallel group, retrospective analysis	Histologically proved curable gastric cancer	D2 vs D2+	Post-operative morbidity and mortality; Operation time; Five-year survival rate	In D4 group, lymph nodes (a1, a2 and b1) were dissected

RCT: Randomized controlled trial.

Table 2 Baseline characteristics of patients in included studies

Study ID (author, yr, ND2/ND2+)	Age (yr) (mean/SD or median/range)			Sex (male/female)			Pathological T stage (serosa negative/positive)			Pathological node status (negative/positive)
	D2	D2+	P	D2	D2+	P	D2	D2+	P	D2	D2+	P
Sano et al 2004[37], Sasako et al 2008[39] (263/260)	60 (25-75)	61(27-75)	> 0.05	176/87	183/77	> 0.05	134/129	146/114	> 0.05	79/184	96/164	> 0.05
Kulig et al 2007[42] (141/134)	56 (31-81)	54 (34-77)	> 0.05	85/56	83/51	> 0.05	64/77	54/84	> 0.05	50/91	56/78	> 0.05
Yonemura et al 2006 and 2008[40,41] (135/134)	63.8 (9.7)	62.5 (10.2)	> 0.05	90/45	91/43	> 0.05	63/72	61/73	> 0.05	37/98	35/99	> 0.05
Jiang et al 2000[36] (32/21)	61 (46-83)	65 (34-84)	NR	19/13	11/10	NR	NR	NR	NR	NR	NR	NR
Maeta et al 1999[43] (35/35)	60 (11)	59 (9)	> 0.05	20/15	21/14	> 0.05	2/33	6/29	> 0.05	15/20	12/23	> 0.05
Hu et al 2009[46] (55/62)	58.8 (11.4)	54.3 (11.4)	< 0.05	42/13	48/14	> 0.05	13/42	15/47	> 0.05	16/39	23/39	> 0.05
Kunisaki et al 2006[45] (430/150)	62.2 (12.5)	59.3 (10.7)	> 0.05	286/144	109/41	> 0.05	197/233	71/79	> 0.05	126/304	34/116	< 0.05
Bostanci et al 2004[44] (100/34)	58.5 (13)	59 (12.6)	> 0.05	63/37	21/13	> 0.05	98/2	29/35	NR	NR	NR	NR

NR: Not reporting.

Table 3 Potential bias of included studies

Study ID (author, yr)	Adequate sequence generation	Allocation concealment	Blinding	Incomplete outcome data addressed	Free of selective reporting	Free of other bias
Jiang et al 2000[36]	Probably yes	Probably yes	Probably yes	Yes	Probably yes	Probably yes
Sano et al 2004[37], Sasako et al 2008[39]	Yes	Yes	Probably yes	Yes	Probably yes	Probably yes
Yonemura et al 2006 and 2008[40,41]	Yes	Probably yes	Probably yes	Yes	Probably yes	Probably yes
Kulig et al 2007[42]	Yes	Probably yes	Probably yes	Yes	Probably yes	Probably yes
Maeta et al 1999[43]	No	No	Probably yes	Yes	Probably yes	Probably yes
Bostanci et al 2004[44]	No	No	Probably yes	Yes	Probably yes	Probably yes
Kunisaki et al 2006[45]	No	No	Probably yes	Yes	Probably yes	Probably yes
Hu et al 2009[46]	No	No	Probably yes	Probably yes	Probably yes	Probably yes