Dietary risk factors for invasive and in-situ cervical carcinomas in Bangkok, Thailand

Objective: Although human papillomavirus (HPV) may be a necessary cause of cervical cancer, most women with HPV infections do not develop this disease. This study was conducted to evaluate the possible effects of specific dietary factors on cervical carcinogenesis. Methods: Fifty hospitalized in-situ cases and 125 controls were identified from family planning or gynecologic clinics associated with Siriraj hospital in Bangkok, Thailand, and 134 hospitalized invasive cases and 384 hospitalized controls from the public wards of Siriraj Hospital were administered a food-frequency questionnaire and tested for HPV DNA in exfoliated cervical cells. Odds ratios in relation to intake of foods high in vitamin C, folate, vitamin E, vitamin A, beta-carotene, retinol, and cruciferous vegetables were estimated using logistic regression in case-control comparisons and in case-case comparisons adjusted for HPV status. Results: High intake of foods rich in vitamin A, and particularly high-retinol foods, were associated with a reduced risk of in-situ disease and less strongly also with a reduced risk of invasive as compared to in-situ disease. No association was found between intake of cruciferous vegetables, foods high in vitamin C, folate, vitamin E, and beta-carotene and risk of either in-situ or invasive cervical cancer. Conclusions: Increasing intake of foods rich in total vitamin A, and particularly high-retinol foods, may reduce risk of in-situ cervical cancer, and at the highest level of intake may inhibit progression to invasion. If others confirm these results they suggest means of reducing the risk of cervical cancer that are amenable to public health action.