Researchers from the University of North Carolina (UNC) at Chapel Hill, US, have identified that wide variations in the mortality risk of breast cancer patients taking aspirin could be related to the DNA methylation profile in their tumours or peripheral blood.

Using data from 1,266 women who participated in the Long Island Breast Cancer Study who were followed for their subsequent mortality, they found a 67% increase in the mortality of those taking aspirin who had methylated tumour promotors of the breast cancer gene 1 (BRCA1), compared with 22-40% for those taking aspirin with an unmethylated tumour promotor of the BRCA1 and progesterone receptor genes.

These findings suggest that methylation profiles in the DNA of a patient’s tumour tissue and peripheral blood are determinants of aspirin’s role in mortality rates. The study could improve the understanding of which patients may benefit from aspirin prescriptions after a breast cancer diagnosis and those who have a higher mortality risk from taking the painkiller.

According to Wiley, UNC at Chapel Hill Gillings School professor of epidemiology Marilie Gammon said: “Our findings, if confirmed, may also impact clinical decision-making by identifying a subgroup of patients, using epigenetic markers, for whom pre-diagnosis aspirin use impacts subsequent mortality, and may help refine risk reduction strategies to improve survival among women with breast cancer.”

Methylation occurs when a methyl group switches some genetic activity in the DNA off and others on. This action and its role in cell death, damage and repair is known to be a contributing cause of cancer over time.

The researchers note the need for further exploration of the impact of aspirin on specific breast cancer patients based on their DNA methylation profiles.

Gammon and lead author TengTeng Wang, who lead the study which at the Gillings School and is now a postdoctoral researcher at Harvard University, noted: “Future research designed to replicate our findings should include a larger sample size to allow examination of patterns of aspirin use, and an enlarged panel of genes to explore the role of genetic predisposition in driving overall genetic instability on survival after breast cancer diagnosis.”

This study was published in the American Cancer Society’s Cancer journal and UNC at Chapel Hill claims it is the first study to investigate the association between DNA methylation in breast cancer patients, aspirin use and patient mortality.

The research was funded by grants from the US National Institutes of Health and conducted in collaboration with researchers from other US universities, such as University of California at Berkeley and Columbia University.