Jin et al. Journal of Experimental & Clinical Cancer Research 2010, 29:18 http://www.jeccr.com/content/29/1/18 Table 1 Main characteristics of all studies included in the meta-analysis Author Year Country Study design Ezzkiouri 2008 Nahon 2008 Repero 2007 Willis 2005 Hellerbrand 2003 Cauza 2003 Boige 2003 Lauret 2002 Beckman 2000 Maroc France Spain England Germany Austria France Spain Sweden Case-control Cohort Case-control Case-control Case-control Case-control Case-control Case-control Case-control C282Y Cases/Controls cases CC CY YY controls CC CY YY HD DD 96/222 103/198 196/181 144/1508 137/233 162/671 133/100 77/359 54/294 95 1 91 12 183 12 119 17 120 17 139 18 126 7 65 12 43 10 0 0 1 8 0 5 0 0 1 219 180 158 1331 223 603 93 337 255 3 0 18 0 23 0 168 9 10 0 63 5 6 1 22 0 38 1 H63D cases HH 59 34 75 28 102 85 108 27 128 31 92 41 52 25 37 17 3 0 9 2 3 0 0 0 Page 3 of 8 controls HH HD 160 60 149 49 124 52 DD 2 0 5 177 52 4 529 133 9 59 40 1 234 92 33 229 59 6 also explored the relationship between H63D and HCC (Table 1). All studies were published between 2000 and 2008. In all studies, the cases were histologically confirmed or diagnosed by elevated AFP and distinct iconography changes (CT, MRI, and B ultrasonography). All the con- trols were free of cancer. The characteristics of the con- trols varied across studies: five studies [8,11,12,15,17] used CLD patients (four studies used LC patients as controls and one study used HCV CH as controls) and seven studies [8,10-12,14,16,31] included healthy popula- tion as controls. LC was diagnosed according to clinical and iconography changes. LC was classified as alcoholic LC and viral LC according to clinical and virology data. HCV was the main etiology of CLD in five studies and only a small proportion of CLD was caused by HBV. Studies were conducted in different ethnicities, mainly in European populations; eight studies [8,10-12,15-17,31] were conducted in populations of European ethnicity, and one study [14] was conducted in Marco Africans. The Hardy-Weinberg equilibrium (HWE) p values of C282Y or H63D genotypes were below 0.05 in the controls of three studies [8,12,17]. The disequilibrium might be caused by population stra- tification or by genotyping errors. The meta-analysis results were then assessed by excluding these studies. Meta-analysis results C282Y The frequency of the C282Y Y allele was 6.17% (136/ 2204) and 5.08% (383/7352) in cases and controls (p = 0.046), respectively, indicating that the variant allele was more frequent in cases. At first, we performed the meta-analysis of nine stu- dies including all controls to explore the association of C282Y polymorphism and HCC. Meta-analysis showed that C282Y polymorphism was associated with HCC in allele contrast model (Y vs. C): FE OR reached 1.50 (95%CI: 1.05-2.14) (Figure 1) (Table 2). There was distinct heterogeneity among studies (p for heterogene- ity = 0.02, I2 = 0.57). Sensitivity analysis showed that the result was not robust. There was no distinct small-study bias among the studies (Egger’s p = 0.39). The meta- analysis of dominant model showed a non-significant increased risk to HCC: RE OR was 1.43 (95%CI: 0.98- 2.07, p for heterogeneity = 0.02, I2 = 0.55). There was no distinct small-study bias among the studies (Egger’s p = 0.68). Of the nine studies that explored C282Y mutation, seven studies used healthy controls, while five studies used chronic liver disease patients as controls. To clarify whether or not C282Y increased HCC in subgroups, we performed subgroup analyses between the comparison of (1) HCC and healthy controls of seven studies, (2) HCC and alcoholic LC patients of four studies, (3) HCC and viral LC patients of four studies. (1) When comparing C282Y polymorphisms between HCC cases and healthy controls of seven studies, allele contrast (Y vs. C) showed association with HCC: RE OR reached 1.61 (95%CI: 1.08-2.39) (figure 2) (Table 2). There was heterogeneity among studies (p for heteroge- neity = 0.04, I2 = 0.55). Sensitivity analysis showed that the result was also not robust (figure not shown). There was no small-study bias among the studies (Egger’s p = 0.65). (2) Four studies used alcoholic LC patients as controls. Four studies included 224 HCC patients with alcoholic LC and 380 alcoholic LC patients without HCC. Meta- analysis provided more distinct association of C282Y polymorphism with HCC among alcoholic LC patients. FE OR reached 4.06 (95%CI: 2.08-7.92, p for heteroge- neity = 0.77, I2 = 0) in the dominant model (Figure 3), and 3.41(95%CI: 1.81-6.41, p for heterogeneity = 0.47, I2 = 0) as allele Y compared with allele C, respectively (Table 2). Sensitivity analyses of two models both gave robust results. Figure 4 showed the sensitivity analysis of the dominant model. There was no small-study bias (Egger’s p: 0.25-0.43).