A case-control study of diet and invasive cervical cancer.

A population-based case-control study was conducted to assess the relation of diet, especially intake of vitamins A, C and E and of folic acid, to the risk of invasive cervical cancer. Cases were 189 women diagnosed with cervical carcinoma between 1979 and 1983 in 3 counties of the Seattle area. Controls (N = 227) were selected through random digit dialling. Diet during the year preceding diagnosis was assessed by interview, using a food frequency questionnaire covering the intake of 66 food items. After adjustment for known risk factors, frequent consumption of dark green or yellow vegetables and of fruit juices was related to a reduced risk of cervical cancer. Similarly, high dietary intake of carotene was associated with a lower risk of the disease, especially of the squamous-cell type. There was an inverse relationship between vitamin C intake and the risk of cervical carcinoma. The adjusted relative risk (RR) was 0.5 (95% confidence interval: 0.2-1.0) for the highest quartile of intake compared to a RR of 1.0 for the first quartile. High vitamin E intake was also related to a reduced risk, the risk for women in the highest quartile being only one-third of the risk for those in the first quartile. Intake of pre-formed vitamin A and of folic acid was not related to the risk of cervix cancer. Thus, our study suggests that the risk of invasive cervical carcinoma might be influenced by some aspects of diet.