HYPERTHERMIA IN CANCER TREATMENT

Hyperthermia
Hyperthermia (also called thermal therapy or thermotherapy) is an acute condition which occurs when the body produces or absorbs more heat than it can dissipate. It is usually caused by prolonged exposure to high temperatures. The heat-regulating mechanisms of the body eventually become overwhelmed and unable to effectively deal with the heat, causing the body temperature to climb uncontrollably.

Hyperthermia can also be created artificially by drugs or medical devices. In these instances it may be used to treat cancer and other conditions. Cancer cells are more heat-sensitive than healthy cells and their structure reacts differently to overheating. In 1910 the possibility of overheating in order to increase the radiation effect on malicious tumors was described for the first time. This already well-known and applied method was rediscovered as so called “whole body hyperthermia” in the beginning of the 1960s. Since the 70s a number of studies were run to further investigate this therapy form.

Research has shown that high temperatures (up to 44°C) can damage and kill cancer cells, usually with minimal injury to normal tissues. By killing cancer cells and damaging proteins and structures within cells, hyperthermia may shrink tumors.

Hyperthermia is almost always used with other forms of cancer therapy, such as radiation therapy and chemotherapy. Hyperthermia may make some cancer cells more sensitive to radiation or harm other cancer cells that radiation cannot damage. When hyperthermia and radiation therapy are combined, they are often given within an hour of each other. Hyperthermia can also enhance the effects of certain anticancer drugs, which is mutually strengthened thereby and a healing more likely – the so-called synergistic effect of hyperthermia. It was found out that cytostatic drugs (chemotherapy substances) clearly act more aggressively at temperatures over 40° C than within the range of the normal body temperature.

There are several methods of hyperthermia , including local, regional, and whole-body hyperthermia.
In local hyperthermia, heat is applied to a small area, such as a tumor, using various techniques that deliver energy to heat the tumor. Different types of energy may be used to apply heat, including microwave, radiofrequency, and ultrasound.
In regional hyperthermia, various approaches may be used to heat large areas of tissue, such as a body cavity, organ, or limb.
Whole-body hyperthermia is used to treat metastatic cancer that has spread throughout the body. This can be accomplished by several techniques that raise the body temperature to 107–108°F, including the use of thermal chambers (similar to large incubators) or hot water blankets.

The effectiveness of hyperthermia treatment is related to the temperature achieved during the treatment, as well as the length of treatment and cell and tissue characteristics. To ensure that the desired temperature is reached, but not exceeded, the temperature of the tumor and surrounding tissue is monitored throughout hyperthermia treatment. Using local anesthesia, the doctor inserts small needles or tubes with tiny thermometers into the treatment area to monitor the temperature. Imaging techniques, such as CT (computed tomography), may be used to make sure the probes are properly positioned.
Most normal tissues are not damaged during hyperthermia if the temperature remains under 44°C. However, due to regional differences in tissue characteristics, higher temperatures may occur in various spots. This can result in burns, blisters, discomfort, or pain. Perfusion techniques can cause tissue swelling, blood clots, bleeding, and other damage to the normal tissues in the perfused area; however, most of these side effects are temporary.
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