Left handedness link to breast cancer

Reported by Susan Aldridge, PhD, medical journalist

Researchers say that being left handed may increase your risk of breast cancer, according to a study of over 12,000 women.
There are many possible risk factors for breast cancer. Now scientists at the University Medical Center at Utrecht, The Netherlands, say that being left handed may increase the risks.

They looked at over 12,000 healthy middle-aged women and took measurements of many different factors like social and economic status, smoking, and family history of breast cancer. This showed that a left-handed woman was more than twice as likely to develop pre-menopausal cancer as a right-handed woman. It may be that exposure to high levels of sex hormones before birth, which influences handedness, also increases the risk of breast cancer in later life. More research, however, is needed into how these hormone levels can affect both being left-handed and the risk of cancer.

Source
BMJ online 26th September 2005

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