6. Summary
In this review, we discussed the main mechanisms that may induce alcohol-related breast cancer. We discussed how ethanol metabolism generates ROS and how these oxidative stress products, together with acetaldehyde, may be involved in breast carcinogenesis. The repair process of the DNA damage induced by acetaldehyde may be modified by genetic polymorphisms in DNA repair genes. Moreover, we discussed how polymorphisms in ethanol metabolism genes may affect breast cancer risk and how mitochondrial ethanol-induced oxidative stress may be related to breast tumorigenesis. The second mechanism discussed was through estrogen metabolism, and we provided evidence as to how alcohol consumption interferes with estrogens, how estrogen metabolism may influence breast carcinogenesis, and how genetic polymorphism in genes involved in estrogen synthesis and metabolism may be related to breast cancer risk. We also reviewed mammographic breast density in relation to alcohol consumption and breast cancer risk. We subsequently discussed folate metabolism and alcohol intake and their effect on methylation status and genetic polymorphisms in one-carbon metabolism genes and their modifier effect on breast cancer risk. Finally, we analyzed p53 mutational spectrum in breast cancers and its relation with alcohol intake.
All the above-described mechanisms by which ethanol is involved in breast carcinogenesis are important and support the complexity of the interaction between alcohol and breast cancer risk.