Case-control study of plasma folate, homocysteine, vitamin B-12, and cysteine as markers of cervical dysplasia

BACKGROUND. An association between B-complex vitamins and related compounds with the development of cervical neoplasia is biologically plausible, yet to the authors' knowledge epidemiologic investigations of these potential b iomarkers are limited. METHODS. A case-control study was designed to examine the relation between plasma folate, homocysteine, vitamin B-12, and cysteine and early, premalig nant changes in cervical epithelial cells among women identified from sever al clinics on Oahu, Hawaii, between 1992 and 1996. Fasting blood samples fo r plasma nutrient analysis, cervical smears for cytologic diagnosis, exfoli ated cervical cells for human papillomavirus DNA testing by polymerase chai n reaction, and a personal interview were obtained from 185 women with atyp ical squamous cells of undetermined significance (ASCUS) of the cervix, 147 women with squamous intraepithelial lesions (SIL), and 191 women with cyto logically normal (Papanicolaou) smears. RESULTS. Age-adjusted and ethnicity-adjusted mean plasma concentrations of cysteine, but not other nutrients, were significantly lower among ASCUS cas es (P = 0.006) and SIL cases (P = 0.01) than controls. A positive trend in the odds ratio for SIL but not ASCUS was found for increased plasma homocys teine concentrations, but this finding was not statistically significant. H igh plasma levels of cysteine were associated with a reduced risk of ASCUS (P value for trend - 0.006), with an odds ratio of 0.3 (95% confidence inte rval, 0.2-0.7) for the highest compared with the lowest quartile of cystein e concentration. A weak, negative relation between cysteine and the develop ment of low grade SIL (LSIL) but not high grade SIL (HSIL) also was found. CONCLUSIONS, The results of the current study do not support the hypothesis that folate, homocysteine, or B-12 are markers of cervical dysplasia risk. A possible inverse association between plasma cysteine concentrations and the risk of cervical dysplasia needs further study. (C) 2000 American Cance r Society.