Table 1.

Statistics on the number of cases and proportion of various subtypes present in the nine studies

	I	II	III	IV	Total
Bertrand et al. [4]	41(44.1%)	21(47.5%)	17(18.3%)	7 (7.5%)	93
Ke et al. [1]	89(47.3%)	39(20.7%)	51(27.13%)	9 (4.8%)	188
Kobayashi et al. [6]	27 (32.1%)	45 (53.6%)	10 (11.9%)	2 (2.3%)	84
Miyamoto et al. [2]	20 (43.5%)	21 (45.7%)	5 (10.8%)	0 (0)	46
Murono et al. [36]	193 (41.2%)	42 (9.0%)	209 (44.7%)	24 (5.1%)	468
Wang et al. [7]	51 (46.3%)	26 (23.6%)	33 (30.0%)	0 (0)	110
Zhang et al. [3]	63 (59.4%)	31 (29.2%)	9 (8.5%)	3 (2.8%)	106
Huang et al. [10]	67 (57.8%)	12 (10.3%)	36 (31.0%)	1 (0.9%)	116
Zhou et al. [11]	58 (55.7%)	12 (11.5%)	32 (30.7%)	2 (1.9%)	104