Hyperthermia

Hyperthermia

What is Hyperthermia? 

Hyperthermia (HT, thermal therapy, thermotherapy) is thought to be one of the cancer therapies amongst surgery, radiation therapy, chemotherapy, gene and immunotherapy. It is a natural or artifi cial phenomenon that involves increasing the temperature of the body or a particular region of it over the threshold temperature set at a particular moment by the thermoregulation system of an organism [1–3]. In the fi eld of oncology HT is considered to be an artifi cial way of increasing the body tissue temperature by delivering heat obtained from external sources to destroy cancerous cells or prevent their further growth. Hyperthermia is mostly identifi ed with a range of temperatures from 40 to 48°C or similar maintained at a treated site for a period of one hour or more.

A core body temperature of more than 104°F (40°C) is defined as hyperthermia. This method of treating cancer has a long history since the Roman and Greek physicians time. In 1893, the best-known study using hyperthermia was done using Coley’s toxin (bacterial toxin) to raise temperature in patients with osteosarcomas and soft tissue sarcomas and reported impressive results with this. The modern use of this modality is to a large extent based on the well documented occurrences of spontaneous remissions in patients with febrile episodes and on extensive laboratory data obtained over the last few years.

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 is monitored throughout hyperthermia treatment

What are the types of Hyperthermia?

  • Local hyperthermia, heat is applied to a small area
  1. External approaches are used to treat tumors that are in or just below the skin. External applicators are positioned around or near the appropriate region, and energy is focused on the tumor to raise its temperature.
  2. Intraluminal or end cavitary methods may be used to treat tumors within or near body cavities, such as the esophagus or rectum. Probes are placed inside the cavity and inserted into the tumor to deliver energy and heat the area directly.
  3. Interstitial techniques are used to treat tumors deep within the body, such as brain tumors. This technique allows the tumor to be heated to higher temperatures than external techniques.
  • Regional hyperthermia, various approaches may be used to heat large areas of tissue, such as a body cavity, organ, or limb.
    1. Deep tissue approaches may be used to treat cancers within the body, such as cervicalor bladder cancer. External applicators are positioned around the body cavity or organ to be treated, and microwave or radiofrequency energy is focused on the area to raise its temperature.
    2. Regional perfusiontechniques can be used to treat cancers in the arms and legs, such as melanoma, or cancer in some organs, such as the liver or lung. In this procedure, some of the patient’s blood is removed, heated, and then pumped (perfused) back into the limb or organ. Anticancer drugs are commonly given during this treatment.
    3. Continuous hyperthermia peritoneal perfusion(CHPP) is a technique used to treat cancers within the peritoneal cavity (the space within the abdomen that contains the intestinesstomach, and liver), including primary peritoneal mesothelioma and stomach cancer.
  • Whole-body hyperthermiais used to treat metastatic cancer that has spread throughout the body. This can be accomplished by several techniques that raise the body temperature.

Why do people use Hyperthermia for cancer?

1.Heat alone- Tumor cell inactivation starts at 40-41 degrees Celsius.

2.Local Regional Heating- Storm et al reported tumor regression in all patients when intratumor temperatures of 46 degrees Celsius or greater was achieved.  The relatively poor blood supply to tumor cells (especially in Chondrosarcoma ) explains the response of tumors to hyperthermia.

3.Heat and drugs- Rates of alkylation of DNA or of conversion of a nonreactive species to a reactive one can increase as temperature increases (e.g. cisplatin )

-Cell killing proceeds at a greatly enhanced rate at high temperatures (e.g. bleomycin and doxorubicin)

4.Hyperthermia as an adjuvant- Studies have shown increased response rates in combination of radiation therapy and hyperthermia, as compared to radiation alone in local regional recurrences in breast cancer, advanced neck nodal metastases from head and neck cancers, and for cutaneous, subcutaneous and peripheral lymph node metastases from melanoma.

In lymph node metastasis of recurrent head and neck cancer, excellent palliation and some complete responses in patients treated with radiation therapy, hyperthermia and cisplatin was studied.

5.Chemotherapy and Hyperthermia- A recently completed phase II trial of locoregional hyperthermia and cisplatin in patients with localized carcinoma of cervix who failed radiation showed a response rate of 52%. Three out of twelve patients became eligible for curative surgery.

Does hyperthermia work?

The responses of tumors to hyperthermia involve both cellular and host related factors. When cells are exposed to elevated temperatures, they are inactivated in a time and temperature dependent fashion. The combination of low pH, low oxygen tension, and lack of glucose and other nutrients tend to make cells extremely responsive to elevated temperatures.

Does Hyperthermia have side effects?

Most normal tissues are not damaged during hyperthermia.  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

Is Hyperthermia safe?

High temperatures can damage and kill cancer cells, usually with minimal injury to normal tissues.

  1. van der Zee J. Heating the patient: a promising approach? Annals of Oncology 2002; 13(8):1173–1184.[PubMed Abstract]
  2. Falk MH, Issels RD. Hyperthermia in oncology. International Journal of Hyperthermia 2001; 17(1):1–18. [PubMed Abstract]
  3. Kapp DS, Hahn GM, Carlson RW. Principles of Hyperthermia. In: Bast RC Jr., Kufe DW, Pollock RE, et al., editors. Cancer Medicine e.5. 5th Hamilton, Ontario: B.C. Decker Inc., 2000.
  4. Wust P, Hildebrandt B, Sreenivasa G, et al. Hyperthermia in combined treatment of cancer. The Lancet Oncology 2002; 3(8):487–497. [PubMed Abstract]
  5. Hyperthermia – description of a method and a review of clinical applications Adam Chicheł, Janusz Skowronek, Magda Kubaszewska, Marek Kanikowski 2007
  6. Principles of Hyperthermia Daniel S.Kapp, PhD, MD, George M.Hahn, PhD, Robert W. Carlson, MD
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