Breast symmetry can be early indicator of breast cancer

Healthy Women who go on to develop breast cancer tend to have less symmetrical breasts than those women who do not develop the disease, researchers at the University of Liverpool have found.

Dr Diane Scutt, Director of Research at the University's School of Health Sciences, studied mammograms - X-rays of the breast - of more than 500 healthy women. Dr Scutt found that those women who went on to develop the disease had less symmetrical breasts than those who did not develop breast cancer.

Dr Scutt examined the difference in volume between the right and left breasts of healthy women, as measured and calculated from their mammograms. This data was combined with other established risk factors such as family history of cancer, to calculate the odds of developing the disease.

They found that the odds of developing breast cancer increased by 1.5 (or 50%) for every 100ml increase in breast volume asymmetry.

Dr Scutt explains: "Symmetry has always been an important part of our biological make up, for example humans and non-humans who are highly symmetrical are preferred as mates over those who are less symmetrical; it is an indicator of health, fitness and performance.

"Humans show symmetry in paired traits such as ear size, digit length and breast volume. Perfect symmetry may be disturbed by a number of factors including the secretion of hormones such as oestrogen. The random deviations from perfect symmetry are termed fluctuating asymmetry (FA). These deviations provide a measure of how the body develops - the more precisely each side develops, the greater the symmetry.

"Breasts are more likely to be disrupted during development because they show rapid growth rates and are highly susceptible to mutation. Symmetrical breast development may well be an indicator of an individual's ability to tolerate 'disruptive' hormonal variation. It is essential that we look more closely at symmetry in mammograms as it may be an important indicator of a woman's risk of developing breast cancer."

Dr Scutt's research is published in Breast Cancer Research.

• Breast cancer is the most common cancer in England. In 2003 there were approximately 36,500 new cases diagnosed, representing 32% of all cancers in women.
• Four in five new cases are diagnosed in women aged 50 and over, with the peak in the 50 to 64 age group.
• Most of the known risk factors for breast cancer relate to a woman's reproductive history such as early first period, late first pregnancy, low number of live-born children and late menopause.
• Other risk factors include oral contraceptive use, hormone replacement therapy (HRT), obesity and increased alcohol consumption.
• http://www.statistics.gov.uk/cci/nugget.asp?id=5751