Effect of GSTM1 polymorphism on risks of basal cell carcinoma and squamous cell carcinoma: a meta-analysis

Glutathione S-transferases are important enzymes in the detoxification of a wide range of reactive oxygen species produced during melanin synthesis and oxidative stress processes. Glutathione S-transferase M1 (GSTM1) null genotype may be a candidate genetic polymorphism with a role in susceptibility to skin cancer such as basal and squamous cell carcinomas. We conducted a systematic review and meta-analysis to define the effect of GSTM1 null polymorphism on skin cancer risk. We searched the PubMed, Embase, and Web of Science databases to identify published case-control studies investigating the association between GSTM1 null genotype and skin cancer risk. Between-study heterogeneity was assessed using the I (2) statistic. Odds ratios (OR) with corresponding 95 % confidence intervals (95 % CI) from individual studies were pooled using fixed and random effects models. Nineteen case-control studies (4,275 cases and 4,255 controls) were considered eligible and included in the meta-analysis, and 11 of which were on basal cell carcinoma; ten, on melanoma, and seven, on squamous cell carcinoma. Overall, the GSTT1 null genotype was not associated with the risk of skin cancer (OR, 1.01; 95 % CI 0.93-1.11; P = 0.76). Subgroup analysis by histological types showed that GSTT1 null genotype was not associated with risks of basal cell carcinoma (OR, 1.06; 95 % CI 0.92-1.21; P = 0.42), squamous cell carcinoma (OR, 0.97; 95 % CI 0.76-1.24; P = 0.80), and cutaneous malignant melanoma (OR, 1.00; 95 % CI 0.88-1.14; P = 0.60). Therefore, this meta-analysis suggests that GSTM1 null polymorphism is not associated with risks of basal and squamous cell carcinomas.