title: IGF-I (CA) repeat polymorphisms and risk of cancer: a meta-analysis.
abstract: Insulin-like growth factor-I modulates cell growth and survival, and is thought to be important in tumor development. A (CA)19 repeat polymorphism in the promoter region of IGF-I gene that may affect transcription activity has been implicated as a risk factor for cancer, but individual studies have been inconclusive or controversial. Therefore, we performed a meta-analysis of 17 studies with IGF-I (CA)19 repeat genotyping on 8,799 patients and 13,901 controls. There were seven studies with prostate cancer (2,307 cases; 2,622 controls), seven studies with breast cancer (3,533 cases; 7,771 controls), and three studies with colorectal cancer (2,959 cases; 3,508 controls). Overall, the random effects odds ratio (OR) for the (CA)19 versus non-(CA)19 allele was 1.03 [95% confidence interval (CI), 0.95-1.11], with some between-study heterogeneity (P < 0.0001). There was no suggestion of an overall effect either in recessive or dominant modeling of (CA)19 allele effects, and the comparison of (CA)19 homozygosity versus non-(CA)19 homozygosity also showed no differential susceptibility to cancer (OR, 0.99; 95% CI, 0.84-1.16). No effect of (CA)19 was seen in subjects of breast cancer (seven comparisons, OR = 1.03; 95% CI, 0.90-1.17, P = 0.005 for heterogeneity), prostate cancer (seven comparisons, OR = 1.08; 95% CI, 0.88-1.27; P = 0.0002 for heterogeneity) and colorectal cancer (three comparisons, OR = 0.96; 95% CI, 0.89-1.03, P = 0.36, no significant between-study heterogeneity). There was also no evidence that the (CA)19 allele associated with the risk of cancer in Caucasians and Asians. The meta-analysis shows that this (CA)19 repeat polymorphism is unlikely to be a major determinant of susceptibility to cancer on a wide population basis. However, a larger single study is required to further evaluate the association IGF-I (CA)19 polymorphisms and the cancer risk in a specific population.
authors.affiliation: Laboratory of Gene Function, School of Life Science, East China Normal University, 200062, Shanghai, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Urology, Shanghai Minghang District Central Hospital, Shanghai, People's Republic of China.
authors.forename: Jianming
authors.initials: J
authors.lastname: Guan
authors.affiliation: School of Life Science, Fudan University, Shanghai, People's Republic of China.
authors.forename: Yuting
authors.initials: Y
authors.lastname: Song
authors.affiliation: Laboratory of Gene Function, School of Life Science, East China Normal University, 200062, Shanghai, People's Republic of China.
authors.forename: Peilin
authors.initials: P
authors.lastname: Chen
authors.affiliation: Laboratory of Gene Function, School of Life Science, East China Normal University, 200062, Shanghai, People's Republic of China.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Zheng
authors.affiliation: Laboratory of Gene Function, School of Life Science, East China Normal University, 200062, Shanghai, People's Republic of China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Tang
authors.affiliation: Laboratory of Gene Function, School of Life Science, East China Normal University, 200062, Shanghai, People's Republic of China. qhwu@bio.ecnu.edu.cn.
authors.forename: Qihan
authors.initials: Q
authors.lastname: Wu
mesh_terms: D001943:Breast Neoplasms / Q000453:epidemiology / Q000235:genetics; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000235:genetics; D004247:DNA / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D008297:Male; D009369:Neoplasms / Q000453:epidemiology* / Q000235:genetics*; D011110:Polymorphism, Genetic; D011471:Prostatic Neoplasms / Q000453:epidemiology / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics*
chemical_list: D007334:Insulin-Like Growth Factor I; D004247:DNA