Diet and the risk of in situ cervical cancer among white women in the United States.

A case-control study of women with incident in situ and invasive cervical cancer was conducted during 1982-83 in five US areas reporting to the Comprehensive Cancer Patient Data System: Birmingham, AL; Chicago, IL; Denver, CO; Miami, FL; and Philadelphia, PA. Controls were selected by random-digit dialing and matched to invasive cases on age, race, and telephone exchange. Of the white non-Hispanic in situ cases and controls identified, 229 (78 percent) and 502 (74 percent) 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 postulated to reduce the risk of cervical cancer: carotenoids, vitamin A, vitamin C, and folate. Weak inverse associations between risk of in situ disease and intake of carotenoids, vitamin C, folate, fruit, and vegetables/fruits were noted but, with further analysis, these seemed attributable to residual confounding by the multiple lifestyle-related risk factors for this disease and possibly to selection bias. Vitamin A and vegetable intake were unrelated to risk. Dark yellow-orange vegetable consumption and duration of multivitamin use were each strongly related to reduced risk of in situ disease (P for trend = 0.02 and 0.002, respectively) and need to be evaluated in other studies. The absence of persuasive protective effects for the four micronutrients and the similar findings from our analysis of invasive cervical cancer do not concur with other epidemiologic studies and suggest that the role of diet and nutrition in the etiology of cervical cancer is not yet resolved.