Left handedness may be associated with an increased risk of breast cancer, say Dutch researchers whose study appears in the British Medical Journal. The study, involving more than 12,000 healthy, middle aged women born between 1932 and 1941, found that left handed women were more than twice as likely to develop pre-menopausal breast cancer as non-left handed women. The researchers said that adjusting for risk factors such as smoking, weight and family history hardly affected the overall association.
Researchers already know that high levels of sex hormones in the womb before birth may induce left handedness in infants. The researchers speculate that these hormone levels may also change the breast tissue. "Although the underlying mechanisms remain elusive, our results support the hypothesis that left handedness is related to increased risk of breast cancer," the researchers concluded.
Further reading: Breast Cancer and Booby Babble
