Table 1.

Main characteristics of studies included in the meta-analysis

Study	Year	Study design	Ethnicity	N	Percentage of LD-SCLC	Percentage of male patients	Age (median)	Age (mean)	Age (range)	Cutoff of NSE (ng/ml)	Treatment	Outcome	NOS
van der Gaast A [25]	1991	Retrospective	Caucasian	70	41.4%	77.1%	63		36–75	12.5	C	OS	7
Johnson PW [26]	1993	Retrospective	Caucasian	154	29.2%	65.0%	63		34–77	25	C,R	OS	7
Fischer JR [27]	1997	Retrospective	Caucasian	52	63.5%	75.0%		58	36–75	30	C,R	OS	6
Shibayama T [28]	2001	Retrospective	Asian	114	59.1%	86.8%	65		29–82	7.5	C,R	OS	6
Jin B [29]	2001	Retrospective	Asian	144	NA	85.4%	62.12		36–86	12.5	C	OS	6
Jean-Louis Pujol [30]	2003	Retrospective	Caucasian	148	39.2%	93.9%	63	61	42–82	17	C,R	OS	7
Bremnes RM [31]	2003	Prospective	Caucasian	436	49.1%	64.2%	64		39–76	13	C,R	OS	7
Ando S [32]	2004	Retrospective	Asian	57	64.9%	84.2%		66	48–78	10.5	S,C,R	OS	6
Xue F [33]	2011	Retrospective	Asian	57	52.6%	68.4%	52.5		29–70	15.2	C,R	OS	6
Zhu H [34]	2015	Retrospective	Asian	281	55.5%	80.4%	57		25–82	18	S,C,R	OS	7
Huang Z [21]	2016	Retrospective	Asian	122	44.3%	75.4%	NA	NA	NA	17	C,R	PFS	6
Wojcik E [35]	2016	Retrospective	Caucasian	63	65.1%	60.3%	59		32–76	35	C,R	OS	6
Jiang X [36]	2017	Retrospective	Asian	107	39.3%	78.5%	63		58.5–68	17	C,R	OS	7
Pan H [37]	2017	Retrospective	Asian	275	NA	87.0%		62.59		81.4	C,R	OS	7
Zhou M [38]	2017	Retrospective	Asian	523	26.8%	79.3%	59		27–87		C,R	OS	7
Liu X [39]	2017	Prospective	Asian	136	43.4%	64.7%		53.3		50.324	C,R	OS, PFS	6
Zhang C [40]	2018	Retrospective	Asian	160	23.8%	80.6%	59		23–83		C	PFS	7
Fan S [41]	2019	Retrospective	Asian	82	NA	81.7%	60		28–82	16.3	C,R	OS, PFS	7

Abbreviations: LD-SCLC limited disease small cell lung cancer, C chemotherapy, R radiotherapy, S surgery, OS overall survival, PFS progression-free survival, NA not available