Very unfortunately, metastatic breast cancer remains largely incurable. Therefore, the primary goals of therapy are the alleviation of symptoms, the avoidance of complications of disease progression, and the prolongation of survival so long as a reasonable quality of life can be maintained. Exceptional circumstances may occasionally offer a more optimistic appraisal. Survival curves for metastatic breast cancer are not normally distributed and some patients can survive well over a decade or longer with a proven diagnosis of metastatic disease. These circumstances are most commonly ER-positive patients with remarkable responses to endocrine therapy. Additionally, so-called Stage IV NED patients may have long secondary disease free intervals and recent data reviewed in Chapter 69 suggest that addition of adjuvant systemic chemotherapy in this setting is likely of benefit.

The consequences of a diagnosis of metastatic disease are so life altering for a patient and her family that we believe, under almost all circumstances, that formal histologic confirmation is required. Furthermore, the determination of specific tumor characteristics such as estrogen, progesterone, and HER2 expression (which clearly can change with or without intervening therapy from determinations on primary tumors) provide an additional indication for biopsy. This is likely to become even more important in coming years as the availability of specific targeted therapies become even more widespread. As reviewed in Chapter, these determinations may soon be reliably obtained on circulating tumor cells or even circulating DNA derived from tumor cells.