MTHFR Gene Polymorphisms as Biomarkers of Ovarian Cancer Risk

Ovarian cancer is the seventh most common cancer in women and leading the cause of death among gynecological cancers (Kristensen and Trope, 1997). The incidence rate vary in both sexes and geographic worldwide. China has a relatively low incidence of 3-5/105 females, which is about one-fourth of the incidence in northern European countries (Jin et al., 1993). The wide geographic variation at an international levels of ovarian cancer in terms of incidence and mortality suggested the role of genetic and environmental factors in the pathogenesis of this cancer. Little is known concerning the etiological factors of the malignancy. Most of the known risk factors are related to parity and family history of ovarian cancer. Reduced ovarian cancer risks are associated with oral contraceptive use and fewer menstrual cycles, while increased risks are associated with infertility, low parity and hormone replacement therapy (Kristensen and Trope, 1997; La, 2001). To our knowledge, folate deficiency resulting from low consumption of vegetables and fruits is related to increased risk of several cancers, including ovarian cancer (Zhang et al., 2004). The carcinogenesis of ovarian cancer by folate deficiency is through two mechanisms ways: one is inducing misincorporation of uracil into DNA to lead to disruption of DNA integrity and DNA repair. Another is causing the alteration in DNA methylation, which could induce the altering expression of critical tumor suppressor genes and proto-oncogenes (Choi and Mason, 2000;