WHAT IS CHEMOTHERAPY?

In simple terms, chemotherapy is a treatment in which an anticarcinogenic agent is taken by the patient. Whereas surgery and radiotherapy are medical treatments against fixed malignancies (cancerous tumors,) chemotherapy can be used to treat cancers spread out all over the body. Examples of this type of cancer are cancer of the blood or malignant lymphatic tumors such as leukemia and cancer of the lymphatic system. Chemotherapy also would be effective against metastasis of localized tumors; the curative value of chemotherapy, therefore, cannot be denied.

At present, chemotherapy is limited in effectiveness due to certain considerations. First of all, the efficacy of various chemotherapeutic agents is strongly dependent on the type of cancer being treated. Second, the toxic effects and side effects are both serious. This is the reason for chemotherapeutic agents’ effectiveness against cancer cells.

The growth of malignant tumors cells (i.e. cell division or mitosis) is identical to that of normal cells. A cell is basically made of protein and genetic material (DNA and RNA.) Anti-cancer drugs aim at destroying either type of genetic material in cancer cells to prevent the tumor from continued growth.

The anti-carcinogens in common use can be classified into 5 categories in the order of their medicinal effectiveness and corresponding to the mechanism by which they accomplish their cytotoxicity. These are:

1. Alkylation agents
These chemicals convert the essential elements necessary for formation of nucleic acid into alkyl compounds to prevent the formation of tumor cell DNA.

2. Metabolism Antagonists
This class of drugs participates in the metabolic processes of the cancer cells and replaces nutrients that the cancer cells need to survive.

3. Anti-cancer antibiont
The target of these compounds is the disruption or prevention of DNA or RNA synthesis.

4. Plant Anti-cancer agent
This agent damages the spindle mechanism upon which cells depend for proper cell division; the cancer cells are thereby prevented from reproduction.

5. Other medicinal agents
Anti-cancer agents developed in recent years, such as cisplatin and adrenocortical hormones, L-asparaginase, etc.

This last category of drugs is administered orally or through injection. Some other, more efficient means of treatment are now under review.

One of these is object selective treatment. In this therapeutic method, the medicine targets a specific cancer focus and has selective toxicity for these abnormal cells. In this method, not only are cancer cells more effectively destroyed, but side effects are also avoided or reduced.

The principal therapies cover::

1. An emphasis on the path of the dose application
Anti-cancer drugs are injected into the body cavity for direct entry into the artery supplying nutrition (artery partial injection treatment)

2. Making use of a dynamic state of blood flow
This is done by means of inserting a balloon to inhibit blood flow in an artery, followed by the injection of an anti-cancer agent, or the use of a pressure raising agent which increases the volume of blood flow in combination with an anti-cancer agent

3. Use of complex anti-cancer agents
In this technique, anti-cancer agents are combined with certain substances and objects that regulate the distribution of the agent and increase its curative effects.