Women with big breasts more likely to develop breast cancer, revealed a genetic study by the California-based genetics firm. Genetic mutations which are associated with breast size are also linked to the development of breast cancer. A number of these genetic mutations are occupied in regulating the female sex hormone oestrogen, which may trigger the growth of breasts as well as tumours.
A US based company23andMe carried out a study involving more than sixteen thousand women of European origin. All the study participants were asked to provide their bra size on a scale of ten-point from smaller to larger. The genetic code of all study participants was read by researchers who glanced through millions of small mutations in their DNA, known as single-nucleotide polymorphisms.
They found seven genetic mutations which were strongly associated with breast size, three among seven were also associated with growth of breast tumour. One of these three mutations regulates the activity of the oestrogen receptor gene which plays a key role in breast growth and in the majority of breast cancer cases.
Another is positioned in an area of a woman’s genome which often shows abnormalities in women suffering with certain types of breast cancer. The association of breast size with breast cancer was seen despite taking into account several factors such as women’s age, pregnancy, breastfeeding history and genetic ancestry.
Study leader Dr Nicholas Eriksson, explained it was the first substantial link between breast size and cancer, but added much more research was needed before it could be considered concrete. The study findings identify genetic variants that have an effect on both breast cancer and natural variation in breast size.
Though the precise relationships between breast size, density, obesity and breast cancer remain difficult to unravel, but, understanding the biology may aid in the development of novel screening tools, added Dr Eriksson. Little is known about the biology of breast size, which researchers believe is only half hereditary, but high oestrogen levels are known to be a risk factor for breast cancer.
The study was published in the journal BMC Medical Genetics.