Journal of Experimental & Clinical Cancer Research 2009, 28:89 http://www.jeccr.com/content/28/1/89 Table 3: Individual and combined WMD, ORs and 95% CIs by IGF-I and IGFBP-3 IGF-1 IGFBP-3 OR (95% CI) % Weight 0.90 ( 0.28, 2.85) 2.5 0.50 ( 0.25, 1.02) 27.8 2.35 ( 1.13, 4.92) 1.1 0.67 ( 0.45, 1.01) 52.6 0.71 ( 0.35, 1.47) 13.1 1.70 ( 0.87, 3.30) 2.8 0.68 ( 0.48, 0.88)100.0 0 1 OR 5 lFGuinrgagupcrhaeicn3creerpresentation of the meta-analysis for IGFBP-3 and Graphic representation of the meta-analysis for IGFBP-3 and lung cancer. The ORs and their 95% confi- dence intervals in the original studies are shown.. WMD(95%CI) --- -4.00(-10.71,2.71) 5.00(-5.65,15.65) -2.00(-9.69,5.69) -8.30(-17.16,0.56) --- -3.04(-7.10,1.02) OR(95%CI) 0.54(0.14,2.07) 0.86(0.47,1.57) 0.64(0.3,11.33) 1.74(1.08,2.81) 0.76(0.39,1.49) 1.21(0.62,2.35) 0.87(0.60,1.13) lege Station, TX) was used for the meta-analysis, using two-sided P-values. Results Characteristics of studies included in the meta-analysis Twenty-two articles were identified by the PubMed and Embase databases search. After reading abstracts and full text of them, 6 articles met the inclusion criteria. All of them are nested case-control within cohort studies as shown in Table 1. Among the 6 studies, 2 studies were conducted in the United States and 4 were done in China, Japan, Finland and British. The number of cases and con- trols ranged from 93 to 230 and 186 to 9,351, respec- tively. The total numbers of cases and controls in these studies were 1,043 and 11,472. Statistical heterogeneity After performing the tests for heterogeneity for IGF-I and IGFBP-3 separately, we decided to use a fixed-effect model References [14] [15] [16] [17] [18] [19] Totol effect ---, not available. Study Lukanova 2001 London 2002 Spitz 2002 Waikai 2002 Ahn 2006 Morris 2006 Overall -5 WMD(95%CI) --- -70.00(-141.14,1.14) 1300.00(-259.41,2859.41) -210.00(-332.13,-87.87) -141.00(-250.77,-31.23) --- -112.28(-165.88,-58.68) OR(95%CI) 0.90(0.28,2.85) 0.50(0.25,1.02) 2.35(1.13,4.92) 0.67(0.45,1.01) 0.71(0.35,1.47) 1.70(0.87,3.30) 0.68(0.48,0.88) to obtain a summary statistic as the tests were not statisti- cally significant (Q-value of 5.86 with df = 5, P = 0.320 for IGF-I and Q-value of 6.66 with df = 5, P = 0.247 for IGFBP-3). Meta-analysis results We abstracted OR comparing the highest category to the lowest and its 95% CI and mean, SD of IGF-I and IGFBP-3, separately. And the data are shown in Table 1 and Table 2. For IGF-I, the results of our meta-analysis and its graphic plot are presented in Table 3 and Figure 1. While compar- ing the highest to the lowest levels of IGF-I in all the stud- ies, the people in the highest strata had a 0.87(95%CI: 0.60~1.13) times higher risk of developing lung cancer. This association was not found to be statistically signifi- cant. Both the Egger's test and Begg's funnel plot did not show any publication bias (P = 0.102; Figure 2). We also examined the possible association of IGFBP-3 and the risk of lung cancer as presented in Table 3 and Fig- ure 3. When we compared the highest to the lowest levels of IGFBP-3, the people in the highest strata had a 0.68(95%CI: 0.48~0.88) times higher risk of developing breast cancer. The association was statistically significant. Similarly, we also did not find any publication bias between the studies (P = 0.502; Figure 4). The individual and combined WMD of IGF-I and IGFBP- 3 are shown in Table 3. We compared circulating levels of IGF-I and IGFBP-3 of lung cancer cases with that of con- trols, the results are the overall WMD = -3.04(95%CI: - 7.10~1.02, P = 0.14) for IGF-I, and WMD = - 112.28(95%CI: -165.88~-58.68, P < 0.0001) for IGFBP-3. The publication bias were also not statisitically significant and the funnel plot were not shown. Sensitive analysis A single study involved in the meta-analysis was deleted each time to reflect the influence of the individual data-set Page 4 of 6 (page number not for citation purposes)