Do alcohol intake and mammographic densities interact in regard to the risk of breast cancer?

Background. The effect of alcohol intake on mammographic densities and the possible interaction between these two factors in regard to the risk of breast cancer were assessed using information from the Breast Cancer Detection and Demonstration Project. Methods. Mammograms taken during the first year of screening for patients whose breast cancer was detected in the 5th year of follow-up (n = 266) and their matched controls (n = 301) were blindly assessed for the percent of mammographic densities, which were measured by planimetry. Results. Among controls, alcohol intake was weakly, positively associated with the percent of mammographic densities (Spearman rank correlation coefficient, 0.09), although the association may have been the result of chance (P = 0.12). After adjustment for confounding factors, the lifetime alcohol intake did not appear to modify the effect of the percent mammographic densities on the risk of breast cancer (P for the interaction, 0.09). Conclusions. Longitudinal studies and larger case-control studies should be conducted to assess the relationship between diet and changes in mammographic densities further.