Table 1 Statistics on the number of cases and proportion of various subtypes present in the nine studies

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