Breast cancer seems to be affecting a larger number of women. An Oxford led study found that increased risk of breast cancer associated with a series of common gene is not linked to lifestyle factors. The various lifestyle factors included use of hormone replacement therapy, age at birth of first child, obesity and alcohol consumption do not affect breast cancer.
Latest studies among the population that carry a small but increased risk of breast cancer have identified many common genetic variations. The Oxford team claim to be the first to have identified effects of these genes may be connected to known lifestyle and behavioral risk factors for breast cancer. The study included 7160 women who were suffering from breast cancer and 10,196 women without breast cancer. Information about their lifestyles and blood samples for genetic testing were imparted by all the women.
“Known risk factors for breast cancer include both lifestyle factors and inherited genetic factors. We looked at whether lifestyle factors for breast cancer, such as use of HRT, alcohol consumption and reproductive history, influence the genetic risks: and the answer is that they do not,” mentioned the study’s main author, Dr Ruth Travis of Oxford University’s Cancer Epidemiology Unit.
The Oxford team examined how the risk of breast cancer associated with 12 common genetic variants in the women’s DNA was expected to vary with 10 well known environmental risk factors for breast cancer. These factors included the number of children, age of the women during first child birth, use of hormone replacement therapy, obesity, breastfeeding and alcohol consumption.
Dr Jane Green, also of the Cancer Epidemiology Unit, adds, “This study provides another piece in the jigsaw, helping us to understand how genes and lifestyle affect breast cancer risk. ‘Genes account for only a small proportion of breast cancers and for most women the main risk factors remain the lifestyle factors such as childbearing, use of HRT, obesity and alcohol consumption. The good news is that some of these are modifiable, so by changing their behavior women can alter their risk of breast cancer.”
None of the 120 comparisons appeared to offer proof on the gene interaction with the environment. This lack of interaction meant that both genetic and environmental factors were probably not dependant on each other; they separately increased the chances of breast cancer. As a contradiction to the first suggestion the risk associated with these common genes were not affected by hormone replacement therapy.
This study did not include common breast cancer genes which affect many women. It included rare breast cancer susceptibility genes BRCA1 and BRCA2. These genes carry high chances of breast cancer but very few women are affected.
The findings are reported in the medical journal The Lancet.