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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:
These chemicals convert the essential elements necessary for formation
of nucleic acid into alkyl compounds to prevent the formation of
tumor cell DNA.
This class of drugs participates in the metabolic processes of the
cancer cells and replaces nutrients that the cancer cells need to
survive.
The target of these compounds is the disruption or prevention of
DNA or RNA synthesis.
This agent damages the spindle mechanism upon which cells depend
for proper cell division; the cancer cells are thereby prevented
from reproduction.
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.
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