Table 1.

Basic characteristics of the studies included

Ref.	Country	Sex (male/female)	Age (yr)	Median follow-up
Cai et al[18], 2000	Japan	52/272	63 mea	24 M
Fukagawa et al[19], 2001	Japan	51/18 vs 22/163	57.8 ± 10.8 vs 59.8 ± 12.11 med	> 36 M
Choi et al[20], 2002	South Korea	37/23 vs 19/93	59 mea	26.3 vs 25.13
Lee et al[21], 2002	Australia	NM	NM	NM
Yasuda et al[22], 2002	Japan	30/14 vs 13/73	NM	> 60 M
Morgagni et al[23], 2003	Italy	111/119	68 med	60 M
Yonemura et al[24], 2007	Japan	198/110	NM	83 M
Kim et al[25], 2008	South Korea	110/43 vs 21/103	54.7 ± 10.8 vs 52.0 ± 12.51 med	83 M
Ishii et al[26], 2008	Japan	23/12	62 med	57.1 M
Kim et al[27], 2009	South Korea	50/40	55.1 ± 12.2 vs 51.6 ± 12.31 mea	49 vs 47 M3
Wang et al[28], 2012	China	43/22 vs 74/523	31.8 ± 10.9 vs 57.9 ± 13.01 mea	45.6 M
Jeuck et al[29], 2015	Germany	51/13 vs 28/33	66.3 mea	56.4 vs 49.23

¹mean ± SD;

²There are a total of 79 patients in this study and 10 patients were excluded because they suffered metastasis;

³Lymph node micrometastasis (LNMM) negative vs positive. med: Median age; mea: Mean age; NM: Not mentioned.