Women with early-stage breast cancer face three late breast cancer consequences: disease recurrence within the conserved breast, development of a contralateral breast cancer, and manifestation of distant metastases. Although local therapy with surgery and radiotherapy is used to minimize the first possibility, adjuvant systemic therapy may theoretically reduce the likelihood of all three events.
In the absence of locoregional or distant metastases, a contralateral breast cancer in a breast cancer survivor is generally regarded as a new cancer rather than a manifestation of disease recurrence.
Several small studies have suggested that a woman's second breast cancer is likely to resemble her first breast cancer. This seems plausible because both cancers arise in a woman with the same genetic, hormonal, and environmental exposures.
The findings if confirmed could have important implications for recommendations about treatment and risk reduction strategies. They give further credence to the goal of individualized strategies that consider attributes of the tumor and the patient. If a woman is at risk for a second breast cancer that is biologically similar to her first cancer, then effective adjuvant systemic therapy may also provide secondary prevention for the contralateral breast.
In the future, new technologies that permit comparison of multiple gene transcripts or proteins should provide more comprehensive insight into the biology of breast cancer, allowing us to ascertain whether the development of contralateral breast cancer is indeed "déjà vu all over again".