ABR                    Breast cancer 

An article written by Duncan Gardham on Mon 26 Sept 2005 in the Daily Telegraph on page 9
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According to today's Telegraph, women who are left-handed are more than twice as likely to contract breast cancer before the menopause, as right-handed women, research has found..  Scientists believe the cause may lie in the exposure to high levels of sex hormones before birth which can induce  left-handedness as well as changes in breast tissue.  Epidemiologists in the Netherlands looked at more than 12,000 healthy middle-aged women as part of their research, published in the British Medical Journal today.  "Although the underlying mechanisms remain elusive, our results support the hypothesis that left-handedness is related to increased risk of breast cancer," said the authors.

Risk factors such as social and economic status, smoking habits, family history and reproductive history were also recorded.  But their results showed that adjusting for risk factors made no difference to the increased chances of left-handed women contracting the disease.  The risk increased to 1.39 times that for right-handed women overall , and 2.41 times for pre-menopausal cancer.  "This risk is compatible with left-handedness being a marker of constitutional risk rather than of environmental risk as with post-menopausal breast cancer."

The cause of left-handedness has previously been attributed to the hormone diethylstilbestrol and the authors suggest that this may also be responsible for the increased risk of breast cancer.

CDC comment    In my pre-retirement occupation I used statistical tools in the estimation of uncertainties of measurement in electrical calibration.  But I have never been happy with statistics.  Like computer software it is an evil art known only to the initiated and taught by demons of the devil.  I am unfortunate in that I am only happy with things I can understand, and my intellect is incapable of grasping the techniques used in statistical analysis.  I think I understand the principle of "risk" as does the whole animal world, but to derive a figure of so-many-times, is to me, a black art.  It is all so theoretical, and can never be proved in practice.  You can be a thousand times more likely to die of something, but if you don't die, you haven't proved anything.