For example, high carrot intake had a relative prostate cancer risk of 1.06 compared to low carrot intake. Tomato sauce was the greatest predictor of subsequent risk of prostate cancer using our 1986 questionnaire and also on a different questionnaire that we administered in 1990. Given that tomatoes and pizza also were related to risk, this does not appear to be a chance phenomenon. This finding seems to be very consistent over time using the three major predictors of lycopene levels. In unpublished data including 500 new cases of prostate cancer in our study participants, tomato sauce is again the major predictor of lower risk.
Tumor biology varies widely in prostate cancer.
Some tumors are very aggressive and others are relatively indolent. The associations in these data were considerably stronger with respect to the aggressive tumors. Relatively few studies have been done on diet and prostate cancer. Mills et al conducted one prospective study in Seventh Day Adventists, which was published I believe in 1989. The questionnaire was rather simple, and at the time, the data did not suggest a lot.