Since there are different forms of the disease, and a woman's cancer may not respond to all of the many standard treatments, there is no single best drug or combination of drugs to treat all metastatic breast cancer patients. But that doesn’t mean that treatment decisons are random or arbitrary, just that they can be complex and individualized. Since no single treatment has the ability to cure or to produce a permanent remission, you’ll be taking a number of different treatments over the course of your disease. When your oncologist thinks about the best way to treat your cancer, the following are among the most important questions that he/she will be considering:
What is the pathology of your cancer?
- Tissue samples taken from your original breast cancer tumor, or from a site of metastasis that has been recently biopsied can reveal what kinds of treatment are likely to work. Tests (assays) for determining ER/PR and HER2 status will be important in determining which treatments may work for you.
- ER and PR Status: If your cancer has many receptors to estrogen and/or progesterone, it is called ER-positive (or PR-positive) or hormone sensitive. That means it is likely to respond to treatments that target these genes, or reduce the amount of estrogen in your body. Some pathologists feel that as few as one percent of estrogen receptors (a small amount that many pathologists would consider ER-negative) may allow for response to anti-estrogenic treatment.
- HER2 Status: Does your cancer over-express the HER2 protein (or does it have multiple copies of the HER2 gene)? If so, this means that it is likely to respond to one of the specific therapies targeted to that gene, like Herceptin (trastuzumab) or Tykerb (lapatinib). This HER2 gene governs the rate of cell growth, or proliferation, so left untreated by these targeted therapies, these types of cancers can be particularly aggressive and fast growing.
How rapidly is your cancer growing?
Where in your body has your cancer spread already?
- Oncologists try to assess the “tempo” of the disease so that they can tell how aggressive the treatment needs to be—for example, should they recommend combined chemotherapy, or might one drug alone be enough to control the disease? Is there time for an anti-estrogenic drug to work, which can take weeks to months, or is a fast-acting chemotherapy called for?
What treatments have you already had?
- How much cancer is present in your body, and where it can be found, are both very important factors in treatment selection.
- A single metastatic site may be treated very differently than widespread disease. You may have only a single spot on your bones, or some cancer in the skin around your surgery scar that looks like a rash, or lump in neighboring lymph nodes.
- Or your cancer may have spread to a vital organ, like your lungs, liver or even your brain.
- Is your cancer in a single site, or in multiple sites? How widely your cancer has spread, how rapidly it is growing there, and how imminent a threat it poses to a vital organ will also be an important factor in your doctors treatment recommendation.
- Because it is typical for metastatic breast cancer to develop resistance to each treatment, or class of treatments, after a period of months to years, your doctor will always be reviewing your treatment history, looking for treatments your cancer has not yet acquired resistance to.
- Is this your first treatment for metastatic breast cancer or have you had several "lines" of treatment?
- Prior adjuvant treatments for primary breast cancer form a part of your treatment history, and will be taken into account.
- Some drugs in the same class as ones you have taken already are "cross-resistant," meaning that if your cancer has acquired resistance to one, the others aren't likely to work. Usually, these are drugs that target a particular function in the cancer cell, in the same or very similar way.