Polymorphisms of GSTM1 and GSTT1, sun exposure and the risk of melanoma: a case-control study.

Glutathione S-transferases (GSTs) are a family of enzymes that are known to play an important role in cellular protection against oxidative stress, including the oxidative stress caused by ultraviolet radiation. This study focused on the possible involvement of GSTM1 and GSTT1 polymorphisms in risk modulation of cutaneous melanoma. Within a case-control study, the presence of the null polymorphism at GSTM1 and GSTT1 was investigated in 188 cases of cutaneous melanoma and 152 controls. Information on socio-demographic characteristics, medical history, sun exposure and pigmentary characteristics were collected for all subjects. Logistic regression was used to estimate odds ratio (OR) and 95% confidence intervals (CI). An interaction was suggested between the GSTM1 and GSTT1 "null" genotype and episodes of sunburn in childhood OR of interaction (1.65, 95% CI (95% CI) 0.27-9.94). The risk of melanoma among the subset of participants who reported sunburns in childhood and who had both null variants, was nine (OR 9.16; 95% CI 1.18-70.9). The results suggest that subjects carrying both GSTM1 and GSTT1 null polymorphisms and experiencing sunburns in childhood have an extremely high risk of melanoma.