The objective of drug therapy is to slow the growth and spread of cancer cells or to destroy them completely. Typically, drug therapy is used for three different purposes:
- To cure cancer with drug therapy alone (lymphomas and testicular cancer, for example)
- Administered after surgery to improve the treatment results and prevent recurrence (typically after the surgical treatment of breast or bowel cancer)
- To prolong life expectancy and alleviate symptoms
The different types of drug therapy applied in cancer treatment can be divided into three groups based on their mechanism of action – cytotoxins, hormone therapy and targeted therapies.
Cytotoxins
Cytotoxins (chemotherapy) prevent cells from dividing and affect cancer cells, in particular, because of their higher tendency to divide. As a result, the cancer cells are killed. Cytotoxins are administered to destroy tumours, improve surgical or radiotherapy results, and to decrease the size of metastases. Additionally, cytotoxins are used to alleviate the symptoms of an incurable cancer and to prolong life expectancy. Cytotoxic drugs are administered intravenously or orally. It is also possible to administer cytotoxic drugs directly to the affected site, into a bladder, spinal canal or pleura, for example. Irrespective of the route of administration, the patient’s hematological values are monitored closely.
Cytotoxins usually cause a variety of side effects, including hair loss, feeling tired, nausea, disorders in stomach functions, and reduced resistance to infections. However, many of these side effects can be treated with new antiemetics and growth factors stimulating bone marrow.
Hormone therapy
Hormone therapy affects cell division. Hormones are administered orally (tablets) or intravenously (injections). Hormone therapy is used for the treatment of cancers, which are stimulated to grow by hormones found naturally in your body. These cancers include breast, prostate and thyroid cancer and cancer of the corpus uteri. The side effects are usually very mild. Tablets are typically administered daily, while injections are given once every one to three months.
Selective drug therapy
Selective drug therapy refers to drugs that affect a particular substance in cancer cells or their function without affecting healthy cells. Selective drug therapy is used as treatment for certain leukemias, cancers of the lymphatic system, small cell lung cancer and breast, kidney, liver and bowel cancers. Compared to chemotherapy, the side effects of selective drug therapy are relatively mild. However, selective drug therapy (antibodies, in particular) is often combined with chemotherapy which does have side effects.