Patterns of Care: Metastatic Breast Cancer
For those who have followed breast cancer drug development over the last decade or so, one striking fact is evident: the majority of state-of-the-art treatments for metastatic breast cancer in use today have received accelerated or full FDA approval since the early 1990s. In order of their approval, these include: Aredia (pamidronate,1991), Taxol (paclitaxel,1992), Navelbine (vinorelbine,1994), Arimidex (anastrozole,1995), Taxotere (docetaxel,1996), Gemzar (gemcitabine,1996), Femara (letrozole,1997), Xeloda (capecitabine,1998), Herceptin (trastuzumab,1998), Aromasin (exemestane, 1999), Zometa (zoledronic acid, 2001), and Faslodex (fulvestrant, 2002). If past history is an accurate predictor, in time, with further clinical research, most of these treatments will go on to become adjuvant treatments for primary breast cancer. Some, like Taxol and Arimidex, have already begun to do so.
There are many more drugs on the way. The Pharmaceutical Research and Manufacturers of America (PhRMA), issues an annual report on new cancer drugs each year. According to latest report, 2003 Survey: Medicines in Development for Cancer,61 there are 395 drugs in development for various cancers, including 49 in breast cancer, and 94 in solid tumors, many of which include breast cancer patients in trials. Among the breast cancer drugs in the research pipeline, several are in late stages of clinical trials investigation. The targeted antiangiogenic therapy Avastin (bevacizumab), reported close to approval in colon cancer, and the growthinhibitor Iressa (gefitinib), recently approved for nonsmall-cell lung cancer, both show promise in breast cancer. And there are quite a few others, including targeted and oral versions of existing cancer therapies reformulated to be work better with fewer side effects.
Many of these new drugs have already supplanted or will supplant older, less effective, and more toxic drugs. Some will represent incremental but real steps in patient care. Others are obvious attempts on the part of manufacturers to hold onto their market share by securing approval for newly-patentable reformulations of drugs that have gone off patent. Some of these new drugs possess entirely new mechanisms of action, and represent novel non-cross-resistant treatment options that may extend life for women with metastatic breast cancer. Eventually, with more clinical trials, most of these treatments will move up to become adjuvant treatments for primary breast cancer.
In addition, most of the drugs used in supportive care have been approved in the last decade or so, like the anti-nausea drugs Zofran (ondansetron, 1991), Kytril (granisetron, 1994), and Anzemet (dolasetron, 1997), and growth-factor support like Nupogen (filgrastim, 1991) and Epogen (Epoetin alfa). Approved this year, the new drug Emend (aprepitant) in combination with other anti-emetics, reduces delayed nausea and vomiting from chemotherapy. In the complex area of pain control, there are continuing refinements and newer drug formulations. The list of palliative and supportive agents is extensive.
As we evaluate these treatments, we also need to understand that Western conventional medicine is not the only form of treatment in use by breast cancer patients. It's important to examine other influences that may pertain to metastatic treatment choices in different populations, taking into account cultural values surrounding life-threatening illness as well as the utilization of alternative and complementary healing practices.