A possible explanation for the inverse association between the null genotypes of GSTM1 and GSTT1 and ovarian cancer risk is that GSTs catalyze the conjugation of reduced glutathione (GSH) to compounds that protect against ovarian cancer or that they bioactivate compounds involved in ovarian carcinogenesis, for instance catechol estrogens [24]. Here, HPGDS is linked to ovarian carcinoma.