We found individuals with GPX1 679T/T genotype (which has been associated with increased risk to certain cancers [99,100]) to have lower plasma Se levels than those with GPX1 679C/C alleles; individuals with the SEPP1 24731 A/A genotype to have 27% greater levels of plasma SEPP1 than those with the SEPP1 24731 G/A or G/G genotypes; and individuals with the SEP15 811 T/C genotype to have greater buccal cell Se levels than those with the SEP15 811 C/C genotype [50]. This evidence concerns the gene GPX1 and cancer.