TUMOR RECURRENCE AND TAMOXIFEN RESISTANCE: WHAT DOES IT MEAN IF THE DOCTOR SAYS MY BREAST CANCER IS NOW DRUG RESISTANT?
Drug resistance is a term used to describe a condition in which cells are able to survive despite drug therapy. There are at least two forms of resistance. In the first variety, called innate resistance, tumor cells are resistant even before any drugs have been given. This kind of resistance is usually not typical of breast cancer but is apt to be found in cancers of the kidney or lung. The second type is called acquired resistance, a condition whereby the cells actually “acquire” resistance following exposure to drugs. The cancer cells are very sensitive to the drugs at first, then become progressively less so. This sort of resistance is most often found in breast cancer. Although patients may at first respond very well to agents such as methotrexate or adriamycin, eventually the drugs stop working because of drug resistance.*39\320\2*
