Breast Volume Asymmetry Value, Ratio, and Cancer Risk

The aim of this study was to investigate the criteria for determining the cancer risk of the breast asymmetry by comparing breast volume asymmetry levels between healthy women and women with cancer.

Two hundred and one women with breast cancer (group 1) were compared with 446 healthy women (group 2) who had no pathologic findings in breast sonography and mammograpy repeated with one-year interval. Data were evaluated retrospectively. Each breast volume was measured twice by Grossman-Roudner Discs. The mean value has been recorded. The amounts of volume difference between two breasts (asymmetry value) and the rates of the volume difference to the breast volume of the smaller side (asymmetry ratio) were compared in both groups.

There was a statistically significant difference between two groups with regard to average age and body mass index (P < 0.01). This significance was decreased but not disappeared, when the comparison was made within the 40-69 age group (P > 0.01). The rate of cases with asymmetry value over 50 mL was significantly higher in the cancer group (P = 0.029). Unfortunately, it disappeared in the 40-69 age group (P = 0.201). The breast volume asymmetry ratio over 20% was significantly higher in the cancer group both in all ages and in the 40-69 age group (P < 0.01). Odds ratio was 2.18 in the entire (all) series and 2.01 in the 40-69 age group. Moreover, there was no significant difference with regard to the rate of tumor location between the smaller or larger side of breast.

Our data show that there is a positive correlation between breast asymmetry ratio over 20% and breast cancer risk. These results need to be confirmed by prospective randomized controlled trials.