Hyperthermia therapy
Encyclopedia
Hyperthermia therapy is a type of medical treatment in which body tissue is exposed to slightly higher temperatures to damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation
and certain anti-cancer drug
s. When combined with radiation therapy
, it is called thermoradiotherapy.
Local hyperthermia for certain small tumors is generally accepted, similar to surgically removing a tumor. Whole-body hyperthermia is generally considered to be a promising experimental cancer treatment
.
Hyperthermia is only useful for certain kinds of cancer, and is not in widespread use. Hyperthermia is most effective when used alongside conventional therapies, so it is normally used as an adjuvant
therapy. The most effective uses are currently being studied.
cells, and is controlled to limit effects on healthy cells. Tumor cells, with a disorganized and compact vascular
structure, have difficulty dissipating heat. Hyperthermia may therefore cause cancerous cells to undergo apoptosis
in direct response to applied heat, while healthy tissues can more easily maintain a normal temperature.
Even if the cancerous cells do not die outright, they may become more susceptible to ionizing radiation therapy
or to certain chemotherapy
drugs, which may allow such therapy to be given in smaller doses.
Intense heating will cause denaturation
and coagulation of cellular
protein
s, rapidly killing cells within a tumor. More prolonged moderate heating to temperatures just a few degrees above normal can cause more subtle changes. A mild heat treatment combined with other stresses can cause cell death by apoptosis
. There are many biochemical consequences to the heat shock response
within in cell, including slowed cell division and increased sensitivity to ionizing radiation therapy
.
Hyperthermia can kill cells directly, but its more important use is in combination with other treatments for cancer. Hyperthermia increases blood flow to the warmed area, perhaps doubling perfusion in tumors, while increasing perfusion in normal tissue by ten times or even more. This enhances the delivery of medications. Hyperthermia also increases oxygen delivery to the area, which may make radiation more likely to damage and kill cells, as well as preventing cells from repairing the damage induced during the radiation session.
Cancerous cells are not inherently more susceptible to the effects of heat. When compared in in vitro studies, normal cells and cancer cells show the same responses to heat. However, the vascular disorganization of a solid tumor results in an unfavorable microenvironment inside tumors. Consequently, the tumor cells are already stressed by low oxygen, higher than normal acid concentrations, and insufficient nutrients, and are thus significantly less able to tolerate the added stress of heat than a healthy cell in normal tissue.
Mild hyperthermia, which provides temperatures equal to that of a naturally high fever
, may stimulate natural immunological attacks against the tumor. However it is also induces a natural physiological response called thermotolerance, which tends to protect the treated tumor.
Moderate hyperthermia, which heats cells in the range of 40 to 42 °C, damages cells directly, in addition to making the cells radiosensitive and increasing the pore size to improve delivery of large-molecule chemotherapeutic and immunotherapeutic agents (molecular weight greater than 1,000 Daltons
), such as monoclonal antibodies
and liposome-encapsulated drugs. Cellular uptake of certain small molecule drugs is also increased. Most local and regional cancer treatments are in this temperature range.
Very high temperatures, above 50 °C (122 °F), are used for ablation
(direct destruction) of some tumors. This generally involves inserting a metal tube directly into the tumor, and heating the tip until the tissue next to the tube has been killed.
(FUS or HIFU), infrared
sauna, microwave heating
, induction heating
, magnetic hyperthermia
, infusion of warmed liquids, or direct application of heat such as through sitting in a hot room or wrapping a patient in hot blankets.
The schedule for treatments depends on the effect desired. After being heated, cells develop resistance to heat, which persists for about three days and reduces the likelihood that they will die from direct cytotoxic effects of the heat. This suggests a maximum treatment schedule of about twice a week. However, if the desired goal is increased radiosensitivity in a poorly oxygenated tumor, rather than directly killing the cells, then application of heat with every radiation treatment is acceptable.
To minimize damage to healthy tissue and other adverse effects, physicians carefully monitor the temperature of the affected area. The goal is to keep local temperatures under 44 °C (111 °F) to avoid damage to surrounding tissues, and the whole body temperatures under 42 °C (108 °F), which is the upper limit compatible with life. These temperatures compare to the normal human body temperature
, taken internally, of about 37.6 °C (99.6 °F).
A great deal of current research focuses on precisely positioning heat-delivery devices (catheters, microwave and ultrasound applicators, etc.) using ultrasound or magnetic resonance imaging
, as well as developing new types of nanoparticles that make them particularly efficient absorbers while offering little or no concerns about toxicity to other tissues. Clinicians also hope to use advanced imaging techniques to monitor heat treatments in real time; heat-induced changes in tissue
are sometimes perceptible using these imaging instruments.
The thermoacoustic (TA) effect refers to the generation of acoustic waves by electromagnetic (EM) irradiation, such as optical or microwave/radio frequency waves. In the past ten years, thermoacoustic tomography (TAT) using pulsed EM excitation has undergone tremendous growth. Energy deposition inside biological tissue through the absorption of incident EM pulses will create a transient temperature rise on the order of 10 mK. In the thermoelastic mechanism of acoustic generation, a sound or stress wave is produced as a consequence of the expansion induced by the temperature variation. Thermoacoustic signals are temperature dependent, which is an ideal characteristic for use in monitoring biological tissue temperature. The thermoacoustic pressure has the following expression
P=ųaHßc2/cp,
where ųa is the microwave absorption coefficient, H is the heating function and can be written as the product of a spatial absorption function and a temporal illumination function, ß is the isobaric volume expansion coefficient, c0 is the speed of sound, cp is the heat capacity. The thermal expansion coefficient defines the fractional changes in the volume of a material with temperature; normally, its value increases almost linearly with temperature except for the lowest temperatures. Thus, the thermoacoustic pressure can be written in the following form:
P=(A+BT)*P0
where A and B is a constant, which can be gotten by the linearship between temperature and thermal expansion coefficient. T is the temperature, P0 is the thermoacoustic pressure at baseline temperature.
The equation demonstrates that the thermoacoustic pressure is directly proportional to temperature where its variation is the reaction of sample thermodynamic parameter changes with heat.
This characteristic of thermoacoustic signals that give us a new method to monitor thermotherapy temperature, has the potential to be developed into a viable alternative to current clinical temperature monitoring device for microwave thermotherapy.
When combined with radiation, hyperthermia is particularly effective at increasing the damage to acidic, poorly oxygenated parts of a tumor, and cells that are preparing to divide. Hyperthermia treatment is most effective when provided at the same time, or within an hour, of the radiation.
Irradiation alone produces a complete response in about 30% of patients. Combining irradiation and hyperthermia increases the complete response rate to about 70% of patients. In the past decade hyperthermia treatments in conjunction with radiation have been used with curative intent in patients with early stage cancers of the breast, head and neck, and prostate. In his observations, James Bicher, M.D., recorded complete response rates were 82% for breast patients, 88% for head and neck, and 93% for prostate patients. Projected 5 year survival rates were 80% for breast patients, 88% for head and neck, 87% for prostate patients.
Whole-body hyperthermia cannot safely reach the temperatures necessary to improve the effectiveness of radiation, and thus is not used with radiation, but it may be useful for chemotherapy and immunotherapy.
. Medical practitioners in ancient India used regional and whole-body hyperthermia as treatments.
During the 19th century, tumor shrinkage after a high fever due to infection had been reported in a small number of cases. Typically, the reports documented the rare regression of a soft tissue sarcoma
after erysipelas
(an acute streptococcus bacterial infection of the skin; a different presentation of an infection by "flesh-eating bacteria"
) was noted. Efforts to deliberately recreate this effect led to the development of Coley's toxin. A sustained high fever after induction of illness was considered critical to treatment success. This treatment is generally considered both less effective than modern treatments and, when it includes live bacteria, inappropriately dangerous.
Around the same period Westermark used localized hyperthermia to produce tumor regression in patients. Encouraging results were also reported by Warren when he treated patients with advanced cancer of various types with a combination of heat, induced with pyrogenic substance, and x-ray therapy. Out of 32 patients, 29 improved for 1 to 6 months.
Properly controlled clinical trial
s on deliberately induced hyperthermia began in the 1970s.
70 promoter.
Two major technological challenges make hyperthermia therapy complicated: the ability to achieve a uniform temperature in a tumor, and the ability to precisely monitor the temperatures of both the tumor and the surrounding tissue. Advances in devices to deliver uniform levels of the precise amount of heat desired, and devices to measure the total dose of heat received, are hoped for.
In locally advanced adenocarcinoma of middle and lower rectum, regional hyperthermia added to chemoradiotherapy achieved good results in terms of rate of sphincter sparing surgery.
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...
and certain anti-cancer drug
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
s. When combined with radiation therapy
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...
, it is called thermoradiotherapy.
Local hyperthermia for certain small tumors is generally accepted, similar to surgically removing a tumor. Whole-body hyperthermia is generally considered to be a promising experimental cancer treatment
Experimental cancer treatment
Experimental cancer treatments are medical therapies intended or claimed to treat cancer by improving on, supplementing or replacing conventional methods ....
.
Hyperthermia is only useful for certain kinds of cancer, and is not in widespread use. Hyperthermia is most effective when used alongside conventional therapies, so it is normally used as an adjuvant
Adjuvant
An adjuvant is a pharmacological or immunological agent that modifies the effect of other agents, such as a drug or vaccine, while having few if any direct effects when given by itself...
therapy. The most effective uses are currently being studied.
Mechanism
Hyperthermia may kill or weaken tumorTumor
A tumor or tumour is commonly used as a synonym for a neoplasm that appears enlarged in size. Tumor is not synonymous with cancer...
cells, and is controlled to limit effects on healthy cells. Tumor cells, with a disorganized and compact vascular
Blood vessel
The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...
structure, have difficulty dissipating heat. Hyperthermia may therefore cause cancerous cells to undergo apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
in direct response to applied heat, while healthy tissues can more easily maintain a normal temperature.
Even if the cancerous cells do not die outright, they may become more susceptible to ionizing radiation therapy
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...
or to certain chemotherapy
Chemotherapy
Chemotherapy is the treatment of cancer with an antineoplastic drug or with a combination of such drugs into a standardized treatment regimen....
drugs, which may allow such therapy to be given in smaller doses.
Intense heating will cause denaturation
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...
and coagulation of cellular
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s, rapidly killing cells within a tumor. More prolonged moderate heating to temperatures just a few degrees above normal can cause more subtle changes. A mild heat treatment combined with other stresses can cause cell death by apoptosis
Apoptosis
Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Biochemical events lead to characteristic cell changes and death. These changes include blebbing, cell shrinkage, nuclear fragmentation, chromatin condensation, and chromosomal DNA fragmentation...
. There are many biochemical consequences to the heat shock response
Heat shock protein
Heat shock proteins are a class of functionally related proteins involved in the folding and unfolding of other proteins. Their expression is increased when cells are exposed to elevated temperatures or other stress. This increase in expression is transcriptionally regulated...
within in cell, including slowed cell division and increased sensitivity to ionizing radiation therapy
Radiation therapy
Radiation therapy , radiation oncology, or radiotherapy , sometimes abbreviated to XRT or DXT, is the medical use of ionizing radiation, generally as part of cancer treatment to control malignant cells.Radiation therapy is commonly applied to the cancerous tumor because of its ability to control...
.
Hyperthermia can kill cells directly, but its more important use is in combination with other treatments for cancer. Hyperthermia increases blood flow to the warmed area, perhaps doubling perfusion in tumors, while increasing perfusion in normal tissue by ten times or even more. This enhances the delivery of medications. Hyperthermia also increases oxygen delivery to the area, which may make radiation more likely to damage and kill cells, as well as preventing cells from repairing the damage induced during the radiation session.
Cancerous cells are not inherently more susceptible to the effects of heat. When compared in in vitro studies, normal cells and cancer cells show the same responses to heat. However, the vascular disorganization of a solid tumor results in an unfavorable microenvironment inside tumors. Consequently, the tumor cells are already stressed by low oxygen, higher than normal acid concentrations, and insufficient nutrients, and are thus significantly less able to tolerate the added stress of heat than a healthy cell in normal tissue.
Mild hyperthermia, which provides temperatures equal to that of a naturally high fever
Fever
Fever is a common medical sign characterized by an elevation of temperature above the normal range of due to an increase in the body temperature regulatory set-point. This increase in set-point triggers increased muscle tone and shivering.As a person's temperature increases, there is, in...
, may stimulate natural immunological attacks against the tumor. However it is also induces a natural physiological response called thermotolerance, which tends to protect the treated tumor.
Moderate hyperthermia, which heats cells in the range of 40 to 42 °C, damages cells directly, in addition to making the cells radiosensitive and increasing the pore size to improve delivery of large-molecule chemotherapeutic and immunotherapeutic agents (molecular weight greater than 1,000 Daltons
Atomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...
), such as monoclonal antibodies
Monoclonal antibodies
Monoclonal antibodies are monospecific antibodies that are the same because they are made by identical immune cells that are all clones of a unique parent cell....
and liposome-encapsulated drugs. Cellular uptake of certain small molecule drugs is also increased. Most local and regional cancer treatments are in this temperature range.
Very high temperatures, above 50 °C (122 °F), are used for ablation
Ablation
Ablation is removal of material from the surface of an object by vaporization, chipping, or other erosive processes. This occurs in spaceflight during ascent and atmospheric reentry, glaciology, medicine, and passive fire protection.-Spaceflight:...
(direct destruction) of some tumors. This generally involves inserting a metal tube directly into the tumor, and heating the tip until the tissue next to the tube has been killed.
Heat sources
There are many techniques by which heat may be delivered. Some of the most common involve the use of focused ultrasoundUltrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
(FUS or HIFU), infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
sauna, microwave heating
Microwave thermotherapy
Microwave thermotherapy, also called microwave therapy, is a type of treatment in which body tissue is heated by microwave irradiation to damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs.- External links :* entry in the...
, induction heating
Induction heating
Induction heating is the process of heating an electrically conducting object by electromagnetic induction, where eddy currents are generated within the metal and resistance leads to Joule heating of the metal...
, magnetic hyperthermia
Magnetic hyperthermia
Magnetic hyperthermia is the name given to an experimental cancer treatment. It is based on the fact that magnetic nanoparticles, when subjected to an alternating magnetic field, produce heat...
, infusion of warmed liquids, or direct application of heat such as through sitting in a hot room or wrapping a patient in hot blankets.
Types
- Local hyperthermia heats a very small area, usually the tumor itself. In some instances, the goal is to kill the tumor by "cooking" it, without damaging anything else. The heat may be created with microwave, radiofrequency, ultrasound energy or using magnetic hyperthermiaMagnetic hyperthermiaMagnetic hyperthermia is the name given to an experimental cancer treatment. It is based on the fact that magnetic nanoparticles, when subjected to an alternating magnetic field, produce heat...
. Depending on the location of the tumor, the heat may be applied to the surface of the body, inside normal body cavities, or deep in tissue through the use of needles or probes. One relatively common type is radiofrequency ablationRadiofrequency ablationRadio frequency ablation is a medical procedure where part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated using the heat generated from the high frequency alternating current to treat a medical disorder...
of small tumors. This is easiest to achieve when the tumor is on a superficial part of the body, which is called superficial hyperthermia, or when needles or probes are inserted directly into the tumor, which is called interstitial hyperthermia. - Regional hyperthermia heats a larger part of the body, such as an entire organ or limb. Usually, the goal is to weaken cancer cells so that they are more likely to be killed by radiation and chemotherapeutic medications. This may use the same techniques as local hyperthermia treatment, or it may rely on blood perfusionPerfusionIn physiology, perfusion is the process of nutritive delivery of arterial blood to a capillary bed in the biological tissue. The word is derived from the French verb "perfuser" meaning to "pour over or through."...
. In blood perfusion, the patient's blood is removed from the body, heated up, and returned to blood vessels that lead directly through the desired body part. Normally, chemotherapy drugs are infused at the same time. One specialized type of this approach is continuous hyperthermic peritoneal perfusionContinuous hyperthermic peritoneal perfusionContinuous hyperthermic peritoneal perfusion is a procedure in which the abdominal cavity is bathed in warm fluid that contains anticancer drugs. It is a kind of hyperthermia therapy....
(CHPP), which is used to treat difficult cancers within the peritoneal cavityPeritoneal cavityThe peritoneal cavity is a potential space between the parietal peritoneum and visceral peritoneum, that is, the two membranes that separate the organs in the abdominal cavity from the abdominal wall...
(the abdomen), including primary peritoneal mesotheliomaPeritoneal mesotheliomaPeritoneal mesothelioma is the name given to the cancer that attacks the lining of the abdomen. This type of cancer affects the lining that protects the contents of the abdomen and which also provides a lubricating fluid to enable the organs to move and work properly.The peritoneum is made of two...
and stomach cancer. Hot chemotherapy drugs are pumped directly into the peritoneal cavity to kill the cancer cells. - Whole-body hyperthermia heats the entire body to temperatures of about 39 to 41 °C. It is typically used to treat metastatic cancer (cancer that spread to many parts of the body). Techniques include infrared hyperthermia domes which include the whole body apart from the head, putting the patient in a very hot room, or wrapping the patient in hot, wet blankets.
Treatment
Moderate hyperthermia treatments usually maintain the temperature for about an hour or so.The schedule for treatments depends on the effect desired. After being heated, cells develop resistance to heat, which persists for about three days and reduces the likelihood that they will die from direct cytotoxic effects of the heat. This suggests a maximum treatment schedule of about twice a week. However, if the desired goal is increased radiosensitivity in a poorly oxygenated tumor, rather than directly killing the cells, then application of heat with every radiation treatment is acceptable.
Controlling temperatures
One of the challenges in thermal therapy is delivering the appropriate amount of heat to the correct part of the patient's body. For this technique to be effective, the temperatures must be high enough, and the temperatures must be sustained long enough, to damage or kill the cancer cells. However, if the temperatures are too high, or if they are kept elevated for too long, then serious side effects, including death, can result. The smaller the place that is heated, and the shorter the treatment time, the lower the side effects.To minimize damage to healthy tissue and other adverse effects, physicians carefully monitor the temperature of the affected area. The goal is to keep local temperatures under 44 °C (111 °F) to avoid damage to surrounding tissues, and the whole body temperatures under 42 °C (108 °F), which is the upper limit compatible with life. These temperatures compare to the normal human body temperature
Normal human body temperature
Normal human body temperature, also known as normothermia or euthermia, is a concept that depends upon the place in the body at which the measurement is made, and the time of day and level of activity of the person...
, taken internally, of about 37.6 °C (99.6 °F).
A great deal of current research focuses on precisely positioning heat-delivery devices (catheters, microwave and ultrasound applicators, etc.) using ultrasound or magnetic resonance imaging
Magnetic resonance imaging
Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...
, as well as developing new types of nanoparticles that make them particularly efficient absorbers while offering little or no concerns about toxicity to other tissues. Clinicians also hope to use advanced imaging techniques to monitor heat treatments in real time; heat-induced changes in tissue
Biological tissue
Tissue is a cellular organizational level intermediate between cells and a complete organism. A tissue is an ensemble of cells, not necessarily identical, but from the same origin, that together carry out a specific function. These are called tissues because of their identical functioning...
are sometimes perceptible using these imaging instruments.
The thermoacoustic (TA) effect refers to the generation of acoustic waves by electromagnetic (EM) irradiation, such as optical or microwave/radio frequency waves. In the past ten years, thermoacoustic tomography (TAT) using pulsed EM excitation has undergone tremendous growth. Energy deposition inside biological tissue through the absorption of incident EM pulses will create a transient temperature rise on the order of 10 mK. In the thermoelastic mechanism of acoustic generation, a sound or stress wave is produced as a consequence of the expansion induced by the temperature variation. Thermoacoustic signals are temperature dependent, which is an ideal characteristic for use in monitoring biological tissue temperature. The thermoacoustic pressure has the following expression
P=ųaHßc2/cp,
where ųa is the microwave absorption coefficient, H is the heating function and can be written as the product of a spatial absorption function and a temporal illumination function, ß is the isobaric volume expansion coefficient, c0 is the speed of sound, cp is the heat capacity. The thermal expansion coefficient defines the fractional changes in the volume of a material with temperature; normally, its value increases almost linearly with temperature except for the lowest temperatures. Thus, the thermoacoustic pressure can be written in the following form:
P=(A+BT)*P0
where A and B is a constant, which can be gotten by the linearship between temperature and thermal expansion coefficient. T is the temperature, P0 is the thermoacoustic pressure at baseline temperature.
The equation demonstrates that the thermoacoustic pressure is directly proportional to temperature where its variation is the reaction of sample thermodynamic parameter changes with heat.
This characteristic of thermoacoustic signals that give us a new method to monitor thermotherapy temperature, has the potential to be developed into a viable alternative to current clinical temperature monitoring device for microwave thermotherapy.
Adverse effects
External application of heat may cause blisters, which generally heal quickly, and burns, which do not. All techniques may result in pain or fatigue. Perfusion and moderate or high levels of hyperthermia can cause swelling, blood clots, and bleeding. Whole-body hyperthermia, which is the riskiest treatment, usually results in diarrhea, nausea, vomiting, fatigue, and other symptoms of sunstroke; it may also cause cardiovascular problems.Effectiveness
By itself, hyperthermia is generally ineffective, with only small numbers of patients receiving lasting benefit. However, it may significantly increase the effectiveness of other treatments.When combined with radiation, hyperthermia is particularly effective at increasing the damage to acidic, poorly oxygenated parts of a tumor, and cells that are preparing to divide. Hyperthermia treatment is most effective when provided at the same time, or within an hour, of the radiation.
Irradiation alone produces a complete response in about 30% of patients. Combining irradiation and hyperthermia increases the complete response rate to about 70% of patients. In the past decade hyperthermia treatments in conjunction with radiation have been used with curative intent in patients with early stage cancers of the breast, head and neck, and prostate. In his observations, James Bicher, M.D., recorded complete response rates were 82% for breast patients, 88% for head and neck, and 93% for prostate patients. Projected 5 year survival rates were 80% for breast patients, 88% for head and neck, 87% for prostate patients.
Whole-body hyperthermia cannot safely reach the temperatures necessary to improve the effectiveness of radiation, and thus is not used with radiation, but it may be useful for chemotherapy and immunotherapy.
History
The application of heat to treat certain conditions, including possible tumors, has a long history. Ancient Greeks, Romans, and Egyptians used heat to treat breast masses; this is still a recommended self-care treatment for breast engorgementBreast engorgement
Breast engorgement occurs in the mammary glands due to expansion and pressure exerted by the synthesis and storage of breast milk.It can be a cause of mastodynia....
. Medical practitioners in ancient India used regional and whole-body hyperthermia as treatments.
During the 19th century, tumor shrinkage after a high fever due to infection had been reported in a small number of cases. Typically, the reports documented the rare regression of a soft tissue sarcoma
Soft tissue sarcoma
A soft-tissue sarcoma is a form of sarcoma that develops in connective tissue, though the term is sometimes applied to elements of the soft tissue that are not currently considered connective tissue.-Risk factors:...
after erysipelas
Erysipelas
Erysipelas is an acute streptococcus bacterial infection of the deep epidermis with lymphatic spread.-Risk factors:...
(an acute streptococcus bacterial infection of the skin; a different presentation of an infection by "flesh-eating bacteria"
Necrotizing fasciitis
Necrotizing fasciitis , commonly known as flesh-eating disease or Flesh-eating bacteria syndrome, is a rare infection of the deeper layers of skin and subcutaneous tissues, easily spreading across the fascial plane within the subcutaneous tissue.Necrotizing fasciitis is a quickly progressing and...
) was noted. Efforts to deliberately recreate this effect led to the development of Coley's toxin. A sustained high fever after induction of illness was considered critical to treatment success. This treatment is generally considered both less effective than modern treatments and, when it includes live bacteria, inappropriately dangerous.
Around the same period Westermark used localized hyperthermia to produce tumor regression in patients. Encouraging results were also reported by Warren when he treated patients with advanced cancer of various types with a combination of heat, induced with pyrogenic substance, and x-ray therapy. Out of 32 patients, 29 improved for 1 to 6 months.
Properly controlled clinical trial
Clinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...
s on deliberately induced hyperthermia began in the 1970s.
Future directions
Hyperthermia may be combined with gene therapy, particularly using the heat shock proteinHeat shock protein
Heat shock proteins are a class of functionally related proteins involved in the folding and unfolding of other proteins. Their expression is increased when cells are exposed to elevated temperatures or other stress. This increase in expression is transcriptionally regulated...
70 promoter.
Two major technological challenges make hyperthermia therapy complicated: the ability to achieve a uniform temperature in a tumor, and the ability to precisely monitor the temperatures of both the tumor and the surrounding tissue. Advances in devices to deliver uniform levels of the precise amount of heat desired, and devices to measure the total dose of heat received, are hoped for.
In locally advanced adenocarcinoma of middle and lower rectum, regional hyperthermia added to chemoradiotherapy achieved good results in terms of rate of sphincter sparing surgery.
See also
- Microwave thermotherapyMicrowave thermotherapyMicrowave thermotherapy, also called microwave therapy, is a type of treatment in which body tissue is heated by microwave irradiation to damage and kill cancer cells or to make cancer cells more sensitive to the effects of radiation and certain anticancer drugs.- External links :* entry in the...
, use of microwave heating to treat cancer - Photothermal TherapyPhotothermal TherapyPhotothermal therapy is an experimental use of electromagnetic radiation that is proposed to treat various medical conditions, including cancer. The basic model for its use is derived in part from photodynamic therapy, in which a photosensitizer is excited with specific band light...
, use of infrared radiation to treat cancer - Photodynamic therapyPhotodynamic therapyPhotodynamic therapy is used clinically to treat a wide range of medical conditions, including malignant cancers, and is recognised as a treatment strategy which is both minimally invasive and minimally toxic...
, which uses light but not heat - Thermotherapy, use of heat for treating other conditions
- Coley's ToxinsColey's ToxinsColey's toxins is a mixture consisting of killed bacteria of species Streptococcus pyogenes and Serratia marcescens, named after William Coley, a surgical oncologist who developed the mixture in the late 19th century as a treatment for cancer.- History :Observations of...
, a bacteria mixture used to generate fevers as an alternative cancer treatment
External links
- Information from the American Cancer SocietyAmerican Cancer SocietyThe American Cancer Society is the "nationwide community-based voluntary health organization" dedicated, in their own words, "to eliminating cancer as a major health problem by preventing cancer, saving lives, and diminishing suffering from cancer, through research, education, advocacy, and...
- Hyperthermia — Cancer therapy hots up article on physics.org