The risk of cervical cancer in relation to serum concentrations of folate, vitamin B12, and homocysteine.

Due to its role in the synthesis and repair of DNA, folate may protect against the development of cervical cancer. Prospective data on the possible association between folate and cervical cancer have been lacking. There is also a paucity of prospective evidence concerning the possible associations between cervical cancer and vitamin B12, which shares pathways with folate, and homocysteine, a marker of low B vitamin concentrations. A nested case-control study was conducted to prospectively evaluate the associations between cervical cancer and serum concentrations of folate, vitamin B12, and homocysteine. Among a community-based cohort of women who donated blood in 1974 for a serum bank in Washington County, Maryland, 39 cases of cervical cancer diagnosed between 1975 and mid-1990 were included in the study (13 cases of invasive cervical cancer and 26 cases of carcinoma in situ). Two controls were matched to each case by age, race, and sex. Stored serum from the cases and controls was assayed for folate, B12, and homocysteine concentrations. For folate, adjusted odds ratios were 1.0, 0.62, and 0.60 for the low to high thirds of the serum concentrations, respectively, a trend in the protective direction that was not statistically significant (P for trend = 0.42). Overall, the results for vitamin B12 tended to mimic those for folate, whereas the associations for homocysteine tended to be in the opposite direction. None of the results of this study were statistically significant, but patterns of the associations are in accord with hypothesized mechanistic pathways concerning B vitamins and cervical cancer.