 |
 |
 |
 |
 |
 |
COMMON QUESTIONS ABOUT BREAST CANCER: WHAT ARE THE DIFFERENCES BETWEEN CYTOTOXIC SYSTEMIC CHEMOTHERAPY AND HORMONAL THERAPY?
The drugs used in cytotoxic chemotherapy differ from hormonal agents in many ways, and their effects on cancer cells are substantially different. In general, cytotoxic drugs work by killing the cancer cells, whereas hormone therapy works by stabilizing cancer cell growth. The complete destruction of cancer cells, resulting in cell death, gives rise to the term "cytotoxic" drug. Conversely, therapy with hormones such as tamoxifen is said to be "cytostatic" in nature, which means that it inhibits cells from dividing further but does not kill them. Because the drugs used in chemotherapy are directly toxic to cells, they are given over a short period of time. In contrast, hormonal agents need to be present at all times in sufficient quantity to inhibit or block the growth of cancer cells. Thus, tamoxifen and similar substances must be taken on a daily basis rather than for just a few doses or cycles.
Chemotherapy also tends to be toxic to normal cells. Even though some of the toxicities can be alleviated by adjusting the dosage, the range of doses within which the drug (or drugs) must be given in order to achieve an antitumor effect without also producing serious damage is extremely narrow. If not enough drug is given, or if the cancer cells are no longer sensitive to chemotherapy, patients may experience many of the side effects of chemotherapy but fail to respond to the treatment. On the other hand, if too much of a cytotoxic drug is given, the patient may have a satisfactory tumor response but risk more severe toxicities, some of which could be life threatening.
*10\320\2*
Cancer