Sometimes, things do not go as we like and breast cancer returns in a different site from the breast - a metastatic site. It's what patients all fear with each little ache and pain, and what your oncologist looks for at each follow up visit. Less common these days is the patient who presents with metastatic disease at the outset - this can be seen with a very aggressive breast cancer, or with a patient who sometimes delays seeking treatment for a primary tumor which has time to develop overt metastases.
Sadly, metastatic breast cancer remains incurable and while some progress has been made we have a lot more room to go.
The identification of HER2 as a therapeutic target and the development of Herceptin - a targeted therapy against HER2 positive breast cancer - has probably been the greatest contribution to metastatic disease in the past ten years.
Metastatic breast cancer can recur in any organ, but most commonly returns in the bone, lung or liver. The "bone only" recurrence tends to have a more favorable prognosis than the organ (visceral) metastatic disease, and the fewer sites of involvement by cancer, generally the better. A lot of organ involvement can be life threatening in the short term.
Several prognostic factors in the metastatic setting can help guide your treatment and be predictive. A long disease free interval (time between the primary breast cancer's detection and the development of metastatic disease) is generally better than a short disease free interval.
One trend that has emerged is the utility of getting a biopsy of a metastatic site. This is becoming more common in clinical practice. One study recently presented underscores the usefulness of getting a biopsy. In this study a group of women who had metastatic disease had examination of their metastatic site and their primary site to look at the expression of "receptors" or biologic predictors of responsiveness to certain therapies. Correlation of the metastatic site to the original primary showed that there was a difference in the estrogen receptor, progesterone receptor, or Her2 receptor (which predicts response to Herceptin) in 18% of the women studied.
Discuss with your doctor if getting a biopsy of a metastatic site is a good option for you. Only your personal physician can weigh all of the facts and determine your plan of treatment.