Methods: An ecologic study of the relationship between the per person supply of animal fat, vegetable fat, and fish fat obtained from the Food and Agricultural Organizations of the United Nations food balance sheets and female breast cancer mortality rates from 1961 to 1986 was carried out using data from 30 countries.
Results: In univariate analysis, a lag period of about 10 years was found for the highest correlations between breast cancer mortality rates and animal fat minus fish fat intake in the age groups 50 years and above. Age classes 50 years and above showed higher correlations between fat intake and breast cancer mortality than those below 50 years over the periods examined. In multiple regression analysis, animal fat minus fish fat intake showed a highly significant positive relationship with the breast cancer mortality rates (P < 0.001) in age groups 50 years and above for all the periods examined. Whenever significant, dietary fish fat intake correlated negatively (P < 0.001) and vegetable fat positively (P < 0.01) with breast cancer mortality. Moreover, a significant positive relationship (P < 0.001) between the change over time in animal fat minus fish fat intake and that in breast cancer mortality was found. To confirm these findings we also examined the correlation between breast cancer mortality and fat consumption data obtained from 46 dietary surveys performed in 17 countries.
Conclusions: Although slightly less significant, the findings corroborate the relationships obtained by using FAO data. Our findings confirm the highly significant positive association between dietary fat and breast cancer mortality. The effect differs according to the type of fat consumed.