Bilateral Breast Cancer: Analysis of Incidence, Characteristics and Outcome of the Disease

Background: Despite the widespread adoption of breast conservation therapy in breast cancer, there is a dramatic increase in the rate of bilateral mastectomy in USA. The aim of this study was to address the incidence of bilateral breast cancer (BBC) and to investigate its characteristics, survival and outcome compared to unilateral breast cancer.Methods: Data was acquired from the prospectively maintained NUI Galway breast cancer database between 1988 and 2008. BBC were then categorized as synchronous (within 12 months) or metachronous cancer (after 12 months of first tumour). SPSS was used for data analysis.Results: The incidence of bilateral breast cancer in our population was 4.4% (112 of 2524). Of those 2.1% were synchronous while 2.3% were metachronous. Compared to unilateral cases, bilateral cancer patients were younger (0=0.021) and had smaller size (p=0.001) and earlier stage (p<0.001) tumours at diagnosis. There were no differences in histological type (p=0.630) and grade (p=0.054)). While there was no significant difference in survival for patients with bilateral compared to unilateral tumour (p>0.05), the synchronous bilateral tumour was associated with poor overall survival (p=0.010) and disease free survival (p=0.013) in comparison to metachronous bilateral tumour.Conclusion: We observed significant differences in bilateral tumour characteristics compared to unilateral disease. Although bilateral synchronous tumour was associated with poor outcome and overall survival, patients with metachronous disease do as well as patients with unilateral tumour. The increasing practice of bilateral mastectomy is not supported by this large single centre experience.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 5033.