Biomedical Engineering Reference
In-Depth Information
19.2 CANCER TREATMENT TECHNIQUES
Currently, there are numerous techniques that are used for cancer treatment. But each technique has
its own limitations and adverse effects [1,2] . Surgical treatment (excision of the tumor) is usually the
first choice of treatment preferred by physicians. However, surgical excision is not effective when
the cancer cells have infiltrated the nearby vital organs or have spread to distant parts of the body
(metastasis). Surgical excision is preferred for the removal of larger tumors. Cryosurgery is another
surgical technique that is used for freezing and killing the tumor cells. It is an alternative to surgical
excision, and it is used to treat tumors that have not spread to distant organs and to treat precancer-
ous or noncancerous lesions. Chemotherapy is the treatment of cancer with anticancer drugs. These
drugs are used as pills, intravenous injections, or topical applications. Chemotherapeutic drugs may
destroy healthy tissue along with cancer cells and carcinomatous tissue (cytotoxicity). The cytotoxic
effect of chemotherapeutic drugs is highest in bone marrow, gonads, hair follicles, and digestive tract,
all of which contain rapidly proliferating cells. The adverse effects of chemotherapy include fatigue,
nausea, vomiting, alopecia (loss of hair), gastrointestinal disturbance, impaired fertility, impaired
ovarian function, and bone marrow suppression resulting in anemia, leucopenia, and thrombocytope-
nia [3,4] . Another technique of cancer treatment is radiation therapy, which uses radiation energy to
destroy cancer cells and reduce the size of tumors. Bone marrow transplantation and peripheral blood
stem cell transplantation are done to restore stem cells that are destroyed by high doses of radia-
tion or chemotherapy. Immunotherapy, sometimes called biological therapy, biotherapy, or biological
response modifier (BRM) therapy, is a treatment technique that utilizes the human body's immune
system to destroy cancer cells [5] . The immune system is stimulated by an outside source such as an
antibody, synthetic immune system proteins, or BRMs. BRMs include interferons, interleukins, col-
ony stimulating factors, monoclonal antibodies, vaccines, gene therapy, and nonspecific immunomod-
ulating agents. Recent research work has been focused on studying gene therapy for cancer treatment.
Gene therapy is an experimental treatment that involves introducing genetic material into the cancer
cells to destroy the cells [6] . Angiogenesis inhibitors are also currently being evaluated in clinical
trials. These are chemicals that inhibit the formation of blood vessels (angiogenesis). Angiogenesis
plays an important role in the growth and spread of cancer cells [7] . New blood vessels act as a
source of oxygen and nutrients to the cancer cells, allowing these cells to grow, invade nearby tissue,
spread to other parts of the human body, and form new colonies of cancer cells. Angiogenesis inhibi-
tors are used to prevent the formation of blood vessels, thereby depleting the cancer cells of oxygen
and nutrients. Hyperthermia (also called thermal therapy or thermotherapy) is a type of cancer treat-
ment technique in which the cancer cells are exposed to high temperatures (up to 113°F). Research
has shown that high temperatures can damage and kill cancer cells with minimal injury to normal
tissues [8] . By damaging proteins and functional structures within cells, hyperthermia destroys can-
cer cells [9] . Hyperthermia may make some cancer cells more sensitive to radiation or harm other
cancer cells that radiation cannot damage. It can also enhance the anticarcinogenic effect of cer-
tain anticancer drugs. Thus, it is almost used with other forms of cancer therapy, such as radiation
and chemotherapy [10] . Hyperthermia is at clinical trial stage currently. Laser therapy uses high-
intensity laser to treat cancer [11] . Laser can be used to shrink or destroy tumors. Laser therapy is
most commonly used to treat superficial tumors on the surface of the body or the lining of internal
organs. Photodynamic therapy is a type of cancer treatment that uses a drug called a photosensitizer
or photosensitizing agent [12] . Photosensitizer is activated by light of a specific wavelength. When
 
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