Cervical Cancer: Nutritional Considerations
Epidemiologic studies suggest that dietary factors may influence risk for cervical cancer. Part of the effect of diet may be attributable to the suppressive action of certain micronutrients on HPV infection, particularly carotenoids (both vitamin A and non-vitamin A precursors), folate, and vitamins C and E. The following factors have been associated with reduced risk:
Fruits and vegetables. A systematic review of evidence linking fruits, vegetables, and some of their bioactive components to protection against cervical cancer graded the evidence as "possible" for vegetables, vitamin C, and many carotenoids (eg, alpha carotene, beta carotene, lycopene, lutein/zeaxanthin, and cryptoxanthin). A possible protective effect against HPV persistence was also determined for the intake of fruits, vegetables, vitamins C and E, and the carotenoids mentioned above. Evidence was also noted as "probable" for retinol and vitamin E, as well as for the roles of folate and homocysteine, in cervical neoplasia (see below).5
Folic acid and other B vitamins. Interactions appear to exist between folate status, mutations in the folate-dependent enzyme methylene-tetrahydrofolate reductase (MTHFR), plasma homocysteine, and HPV that may reduce cervical cancer risk. Lower red blood cell levels of folate have been associated with a 5-fold greater risk for HPV-related cervical dysplasia.6 A combination of factors that increase folate requirement (MTHFR polymorphism and pregnancy) was associated with a 23-fold greater risk for cervical intraepithelial neoplasia, compared with nulliparous women with the normal MTHFR genotype.7
Blood levels of homocysteine may increase with MTHFR genotype, and hyperhomocysteinemia is associated with a 2.5-to-3 times greater risk for invasive cervical cancer.8 HPV increases the risk for cervical neoplasia almost fivefold, above a homocysteine level of roughly 9 mumol/l.9 Other studies showed that circulating levels of vitamin B12 were inversely associated with HPV persistence,10 and that B12 supplements were inversely associated with high-grade squamous intraepithelial lesions of the cervix.11
Food sources of vitamin E. The review cited above describes evidence of a protective effect of high blood levels of vitamin E as "possible" for HPV persistence and "probable" for cervical neoplasia.5
In addition, obese women appear to have a modestly higher risk for cervical adenocarcinoma, which represents 15% of cervical cancers. Mortality from cervical cancer overall is also increased in obese patients.12
While an important body of research on diet and cervical cancer risk exists, there has been little research on the role of diet in survival after diagnosis.
What to Tell the Family
Cervical cancer is fairly easily treated if detected early. For this reason, Pap evaluations should be conducted on the schedule recommended by the primary health care provider. Cervical cancer risk is closely tied to cancer-causing forms of the human papillomavirus (HPV). HPV infection may be chronic or transient, and is affected by diet, tobacco use, and genetic factors. Men can also be screened for HPV. Risk of cervical cancer is reduced by avoiding multiple sexual partners and maintaining a diet of fruits and vegetables especially high in carotenoids and foods high in folic acid (legumes, whole grains, fruits, and vegetables).
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