Problems faced by evidence-based medicine in evaluating lymphadenectomy for gastric cancer

Table 1 Short-term results of gastric cancer surgery with D2 lymphadenectomy in Eastern Asia vs Europe, in clinical trials vs observational studies[16]

	Post-operative mortality	Post-operative morbidity	Median nodes retrieved	Adequate staging (≥15 nodes)
Eastern Asia
Trials	0%-0.8%	17%-21%	54	100%
Observational	< 2%	-	-	-
Europe
Trials	5%-14%	43%-46%	17	-
Observational	2%-5%	21%-35%	25-26	86%-95%
IRGGC (VR, SI, PD)	3.6%	33.6%	29 (IQ 21-38)	93.8%

IRGGC: Italian Research Group for Gastric Cancer.

Table 2 Summary of the systematic review of studies, comparing limited (D1) and extended (D2) lymphadenectomy and published in 2008-2012 on journals indexed by Journal Citation Reports. Articles were weighted according to 5-year impact factor (2008-2012)

Authors	Country	Journal	Year	Study design	5-yr IF
Further studies	Further studies needed
Catalano et al[40]	Italy	Crit Rev Oncol Hematol	2009	Expert opinion	4.562
Coburn[41]	Canada	J Surg Oncol	2009	Review	2.710
D’souza et al[42]	India	J Cancer Res Ther	2009	Review	0.7611
Songun et al[43]	The Netherlands	Expert Rev Anticanc	2009	Expert opinion	2.055
Yoon et al[44]	United States	Oncologist	2009	Expert opinion	5.245
Coburn[45]	Canada	J Surg Oncol	2010	Expert opinion	2.710
de Bree et al[46]	Greece	J Surg Oncol	2010	Review	2.710
Degiuli et al[47]	Italy	Brit J Surg	2010	Clinical trial	4.956
Tanizawa et al[48]	Japan	Gastric Cancer	2010	Review	3.615
Maduekwe et al[49]	United States	J Gastrointest Surg	2011	Review	2.766
Doglietto et al[50]	Italy	Ann Ital Chir	2012	Expert opinion	0.286
Hundahl[51]	United States	Surg Oncol Clin N Am	2012	Review	1.162
Vallbohmer et al[52]	Germany	Curr Prob Surg	2012	Expert opinion	2.267
Overall					35.805
D2 not favoured	D2 not favoured over D1
Lustosa et al[53]	Brazil	Acta Cir Bras	2008	Meta-analysis	0.695
Van Cutsem et al[54]	EORTC2	Eur J Cancer	2008	Expert opinion	5.257
Yang et al[55]	China	Am J Surg	2009	Meta-analysis	2.727
Memon et al[56]	Australia	Ann Surg	2011	Meta-analysis	8.264
Wong et al[57]	United States	Curr Treat Option On	2011	Expert opinion	2.4221
Overall					19.365
D2 favoured	D2 favoured over D1
Ozmen et al[58]	Turkey	J Surg Oncol	2008	Review	2.710
Díaz de Liaño et al[59]	Spain	Clin Transl Oncol	2009	Observational	1.316
Griniatsos et al[60]	Greece	World J Gastroenterol	2009	Observational	2.594
Kodera et al[61]	Japan	Acta Chir Belg	2009	Review	0.499
Roy et al[62]	India	Indian J Surg	2009	Review	0.0921
Sasako et al[63]	Japan	Jpn J Clin Oncol	2010	Expert opinion	2.063
Shi et al[64]	China	J Surg Oncol	2010	Review	2.710
Songun et al[65]	The Netherlands	Lancet Oncol	2010	Clinical trial	21.856
Tentes et al[66]	Greece	J BUON	2010	Observational	0.653
Hussain[67]	United Kingdom	Curr Opin Gastroen	2011	Expert opinion	3.739
Meyer et al[68]	Germany	Dtsch Arztebl Int	2011	Expert opinion	2.988
Ott et al[69]	Germany	Langenbecks Arch Surg	2011	Review	1.970
Saka et al[70]	Japan	Jpn J Clin Oncol	2011	Review	2.063
Lee et al[71]	Korea	Yonsei Med J	2012	Review	1.214
Sasako[72]	Japan	Surg Oncol Clin N Am	2012	Expert opinion	1.162
Seevaratnam et al[73]	Canada	Gastric Cancer	2012	Meta-analysis	3.615
Viudez-Berral et al[74]	Spain	Rev Esp Enferm Dig	2012	Expert opinion	1.208
Overall					52.452

¹2012 impact factor was used, as the 5-year impact factor was not available;

²EORTC: European Organisation for Research and Treatment of Cancer.