Table 3.

Quality assessment of the included prospective controlled clinical trials based on the Newcastle-Ottawa scale

Study	Selectiona			Comparabilityb		Outcome assessmentc		Score
	1	2	3	4#	5	6	7
Iizuka	*		*	*	**	*		6
Kobayashi	*		*		*	*		4
Nakae	*	*	*		*	*		5
Saito	*	*	*	*	*	*	*	7
Tajika	*	*	*	**	**	*		8
Terasaki	*		*	*	*	*		5
Sudo	*		*		*	*		4
Lee	*	*	*	*	**	*	*	8
Coumaros	*	*	*		*	*		5
Kang	*		*		*	*	*	5
Kudo	*		*		*	*		4

^aSelection: (1) assignment for treatment (if yes, one point). (2) How representative was the ESD group in comparison to the general population undergoing treatments (if yes, one point; no points if the patients were selected or selection of group was not described). (3) How representative was the EMR group in comparison to the general population undergoing treatments (if yes, one point; no points if the patients were selected or selection of group was not described).

^bComparability: (4) group comparable for 1–2 (if yes, two points; one point if one of these two characteristics was not reported even if there were no other differences between the two groups and other characteristics had been controlled for; no points were assigned if the two groups differed). (5) Group comparable for 3–5 (if yes, two points; one point if one of these three characteristics was not reported even if there were no other differences between the two groups and other characteristics had been controlled for; no points were assigned if the two groups differed). Comparability variables: 1 = age, 2 = gender, 3 = tumor location, 4 = stage, 5 = procedure.

^cOutcome assessment: (6) clearly defined outcome of interest (if yes, one point for information ascertained by medical records or interview; no points if this information was not reported). (7) Follow-up equal between the two groups (if yes, one point; no points if follow-up not reported).

^#It was not possible to evaluate the American Society of Anesthesiology Score.