Breast cancer linked to bra size

Women with larger breasts are more likely to develop breast cancer scientists now believe.Breast cancer linked to bra sizeA study of more than 16,000 women found those with a larger bra size were at greater risk of the disease.

The link could be down to the sex hormone oestrogen that can trigger the growth of mammary glands and tumours.

The researchers found seven genetic factors significantly associated with breast size – three of which are strongly correlated with mutations already linked to breast cancer.

Dr Nicholas Eriksson said: “One of the variants is known to regulate the expression of the oestrogen receptor gene which plays a vital role in breast growth and in the majority of breast cancer cases.

“Another one of these mutations is located in a region of the genome that often shows abnormalities in people with a certain subtype of breast cancer.”

He used data from his California-based personal genetics company 23andMe to make the first concrete link between breast size and breast cancer risks.

His findings, Genetic variants associated with breast size also influence breast cancer risk published online in BMC Medical Genetics, are based on the participants answers to survey questions including bra cup size and bra band size and comparing them with genetic data on millions of mutations.

Dr Eriksson said: “Social norms and preferences aside, it turns out that breast size matters – but not quite in the way you think.  The paper shows genetic factors influence whether women have double As or double Ds.”

“This might sound a bit frivolous at first but our research uncovered surprising connections between the genetics of breast size and the genetics of breast cancer.”

“In our case, no one’s personal space was violated – all of our data was self-reported by female 23andMe customers of European descent who have opted into research and filled out an online survey.

“We specifically asked about bra cup size as an approximation for breast size using a 10-point scale ranging from ‘Smaller than AAA’ to ‘Larger than DDD.'”

His team also took into account age and breast-related surgeries including augmentation or reduction.

Dr Eriksson said: “Most of the genetic factors we identified for breast size lie in regions of great importance for breast cancer.

“These findings show some of the same biological pathways underlie both normal breast growth and breast cancer.

“This isn’t a huge surprise if you think of cancer as unrestrained growth. But the relationship between breast size and breast cancer is complicated.

“Some studies have found that larger breast size as a young woman is associated with a slight increase in breast cancer risk, but only in women who were lean at a young age. The genetic factors we found aren’t enough to explain this association, but support the idea that breast size and breast cancer are related.”

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