Recently, I chanced upon a paper in the PLoS Genetics journal by two research groups from Brown University and the University of California San Francisco.  Their findings suggest that epigenetic changes to DNA in breast cancers are related to environmental risk factors and tumour size.  The information gleaned might also help predict the severity of the disease.

According to Wikipedia:

"Epigenetics is the study of inherited changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the underlying DNA sequence, hence the name epi- (Greek: επί- over, above) -genetics."

Personally, I think of it in more simple lay terms as the control of patterns of gene expression in cells.

In this research, epigenetic profiles in stage I to IV breast tumours from 162 women were measured.  A detailed assessment of individual demographic and dietary information was recorded, as well as breast cancer tumour characteristics. The tumour epigenetic signatures were used to provide more detailed staging, and eventually, prediction of prognosis, although further work was encouraged for the latter.

What was interesting was the study found that alcohol consumption, folate intake (vitamin B9), and tumour size are each independently associated with epigenetic profiles of tumours:

"In fact, strong evidence of an etiologic role for alcohol in breast cancer has been reported in multiple meta-analyses of prospective and case-control studies with an excess risk for each alcoholic drink per day of about 10%."

While alcohol had a negative effect, folate consumption appeared to have a positive effect:

"Yet, metaanalysis of case control studies of dietary folate, including results from the Shanghai Breast Cancer Study (whose participants are not regular alcohol drinkers) generally support a protective role for folate."

The data in this study confirmed previous research on the effects of alcohol and folate on breast cancer risk by comparing the DNA methylation patterns:

"Breast cancer prognostic characteristics and risk-related exposures appear to be associated with gene-specific tumor methylation, as well as overall methylation patterns."
Christensen, B., Kelsey, K., Zheng, S., Houseman, E., Marsit, C., Wrensch, M., Wiemels, J., Nelson, H., Karagas, M., Kushi, L., Kwan, M., & Wiencke, J. (2010). Breast Cancer DNA Methylation Profiles Are Associated with Tumor Size and Alcohol and Folate Intake PLoS Genetics, 6 (7) DOI: 10.1371/journal.pgen.1001043

Shrubsole MJ, Jin F, Dai Q, Shu XO, Potter JD, Hebert JR, Gao YT, & Zheng W (2001). Dietary folate intake and breast cancer risk: results from the Shanghai Breast Cancer Study. Cancer research, 61 (19), 7136-41 PMID: 11585746