Prognostic factors for metachronous contralateral breast cancer

2-20% of breast cancer patients develop a tumor in the contralateral breast. Contralateral breast cancer is today treated as a new primary tumor. The impact of the biological relationship between the first and second breast cancer, as well as the impact of adjuvant systemic therapy after the first primary tumor, on the patient’s prognosis after the second tumor, is debated.
We are currently studying the importance of tumor characteristics and adjuvant therapy for prognosis after the second cancer in a material of 727 patients with contralateral breast cancer, diagnosed 1977-2007. By using second generation sequencing techniques we are also evaluating the possibility to determine whether the contralateral breast cancer is a new primary tumor or a metastatic lesion from the first tumor.