The relationship between breast asymmetry, breast size and the occurrence of breast cancer.

Breast cancer is the second most common cancer among women in the world and in developed countries it is the most common. The early identification of women at risk is therefore of great importance and any additional measures which may aid diagnosis, particularly in high risk groups, would be of benefit. Breast volume and breast asymmetry were calculated from mammograms of 250 women with breast cancer and compared with those of 250 age-matched controls. There was evidence that breast cancer patients had more breast asymmetry and larger breasts than age-matched healthy women. The former observation is the first evidence that high breast asymmetry may be a risk factor for breast cancer. Breast asymmetry is likely to be a predictor of, rather than the effect of breast cancer.