GST polymorphisms interact with dietary factors to modulate lung cancer risk: study in a high-incidence area.

The aim of this study was to explore possible correlations between glutathione S-transferases (GST) polymorphisms, smoking, diet, and lung cancer susceptibility in a rural Spanish region with one of the highest incidence rates of the country. All lung cancer patients living in the area (103) and 247 matched controls were genotyped for the GST mu 1 (GSTM1) null, GST theta 1 (GSTT1) null, and GST pi 1 (GSTP1) Isoleucine (Ile) 105 valine (Val) polymorphisms and interviewed to gather information on smoking and dietary habits. Neither the presence of GST polymorphisms nor their interaction with smoking was independently associated to lung cancer risk. The intake of carotenoid-rich red and yellow vegetables was inversely associated with lung cancer (P < 0.05). Interestingly, this was observed only in carriers of the GSTM1 (P = 0.04), GSTT1 (P = 0.03), or GSTM1/T1 (P = 0.04) positive genotypes. Similarly, the consumption of citrus fruits was more frequent among cancer-free subjects who carried functional GSTM1 (P = 0.04) or both GSTM1 and GSTT1 enzymes (P = 0.04). The results show that the inverse association observed between the intake of dietary carotenoid-rich vegetables and lung cancer risk is dependent on the GST genotype. These results warrant further investigations to confirm the observed associations.