Diet and the risk of invasive cervical cancer among white women in the United States.
A case-control study of incident invasive cervical cancer was conducted in Birmingham, Alabama; Chicago, Illinois; Denver, Colorado; Miami, Florida; and Philadelphia, Pennsylvania, during 1982-1983. Controls were selected by random-digit dialing and were matched to cases by age, race, and telephone exchange. Of the white, non-Hispanic cases and controls identified, 271 (73%) and 502 (74%), respectively, were successfully interviewed. Diet was assessed by asking about the usual adult frequency of consumption of 75 food items and the use of vitamin supplements. Included were the major sources of the four micronutrients believed to reduce the risk of cervical cancer: carotenoids, vitamin A, vitamin C, and folate. Women in the highest quartiles of intake of each of these micronutrients had adjusted relative risks of invasive squamous cell cervical cancer comparable to those of women in the lowest quartiles, although their micronutrient intake was estimated to be 3-4 times as high. Risk was not affected by increased consumption of vegetables, dark green vegetables, dark yellow-orange vegetables, fruits, or legumes, or by high intake of the basic food groups. These generally negative findings stand in contrast to findings in previous epidemiologic studies, and the discrepancy is not readily explained by bias, uncontrolled confounding, or inadequate power. The question of the role of diet and nutrition in the etiology of cervical cancer is not yet resolved.