Hyperthermia Therapy

What is Hyperthermia?

Hyperthermia is the term used to describe overheating (coming from the Greek language). In contrast to fever, which is regulated and generated by the body, hyperthermia is an increase in body heat (general or site-specific) from outside. This overheating is capable of killing cancer cells or making them more sensitive to radiation therapy.

A particular influence of temperature on the processes in the body has been known for a long time. In the past, for example, fever-increasing (pyogenic) agents have been explicitly given for certain diseases. Among others, the Nobel Prize for Medicine was awarded in 1927 for the fever-inducing therapy of syphilis.

It is also known that the body generates fever in the case of infections because the body's defense works better at a higher temperature. At the same time, too high a temperature is also dangerous because above a temperature of 42 degrees Celsius, the protein, as an essential component of the body, degenerates.

When Is Hyperthermia Therapy Recommendable?

Hyperthermia is an additive therapy that is used in combination with radiation or chemotherapy. Although direct killing by heat would be possible, it would cause severe damage to healthy body tissue.

Hyperthermia makes the tumor cells sensitive to the radiation therapy that follows later. The reason this works is based on the biology of many types of cancer. Due to their rapid growth, cancerous tumors are often undersupplied in some areas because the blood vessels cannot grow back fast enough. In this case, heat leads to a kind of heat stress. In subsequent radiotherapy, the stressed cells can be eliminated more efficiently. In this way, parts of the tumor are also made sensitive to radiation that would have survived previously with radiation therapy alone.

In Which Types of Cancer, Can Hyperthermia Be Used?

Cancer types that can be considered for this combination of therapies are tumor types for which radiation therapy alone is also one of the primary therapy options.

Hyperthermia therapy can be considered for the following tumors:

• Breast wall recurrence in breast cancer
• Superficial breast tumors
• Malignant melanoma
• Rectal carcinoma
• Anal carcinoma
• Prostate cancer
• Advanced cervical cancer
• Advanced bladder cancer
• Specific head and neck tumors

An interview with Professor Bodis on the status of hyperthermia in cancer treatment can be found here.

Costs of Hyperthermia Therapy

It should be noted that hyperthermia is not yet one of the standard therapies for cancer, so that the expenses must be agreed with the health insurance company. In most cases, hyperthermia is used in clinical studies in large university hospitals. There are still only a few devices for treatment on the market, and mass production will probably take some time.

How Does the Hyperthermia Treatment Work?

In the beginning, there is usually an interdisciplinary review of each cancer case, where doctors of internal medicine (internists), oncologists (specialists for tumor diseases), surgeons, and possibly radiotherapists meet. In consultation with the patient's wishes, the best possible treatment option is explored.

If it is decided on a combination of hyperthermia and radiotherapy, the patient will be referred to the radiotherapist, who will explain the procedure in detail and point out the risks and side effects separately.

Hyperthermia is carried out with electromagnetic waves (microwaves, radio waves) or ultrasound waves. These waves generate heat (similar to a microwave oven). Depending on the type of tumor, different variants of hyperthermia are used.

Whole-Body Hyperthermia

In whole-body hyperthermia, the entire body is heated, which is particularly essential if cancer has already spread to different parts of the body (metastases). Usually, this variant is only carried out within studies, so only a little information on side effects and prognosis is known.

Surface Hyperthermia

Local or surface hyperthermia is used far more frequently. Electromagnetic waves or ultrasound are applied to areas on the skin surface or directly below. Especially superficial forms of breast cancer (mamma carcinoma), as well as skin tumors, or metastases in the area of the skin can be treated, where hyperthermia is used either alone or in combination with radiotherapy.

Deep Hyperthermia

Equally conventional is the regional or deep hyperthermia, which involves heating larger areas around the tumor. Deeper lying areas and metastases of cancer can be reached with this procedure. This variant is used mainly in the rectum or for tumors in the abdominal cavity. During the treatment, the patient lies on a couch; a ring applicator emits the radiation by moving over the patient. For better conduction of the rays, the patient lies on a water cushion, because water has a high conductivity.

Interstitial Hyperthermia

Another variant is interstitial hyperthermia. Similar to brachytherapy (a type of radiation therapy), one or more probes are placed in the tumor. Through this probe, the electromagnetic waves can now be applied directly into the tumor and take effect. The probe can be placed directly into tumors that are accessible from the outside (such as prostate cancer or various head and neck tumors). Otherwise, the probes must be placed under light anesthesia.

The latest achievement is a form of hyperthermia with magnetizable nanoparticles of iron. The iron accumulates mainly in tumor tissue. The heating of the nanoparticles can be controlled by magnetization from outside via an electromagnetic field. This variant has only been tested in clinical studies with brain tumors so far.

Side Effects and Risks of Hyperthermia Therapy

Any kind of overheating is unpleasant for the person. The heat receptors sound the alarm and release pain messengers. Unfortunately, this side effect cannot be avoided with hyperthermia either. Painkillers can be given to calm the patient down, or the treatment can take place under light anesthesia.

Besides, the temperature in the treated area is checked by temperature probes that are inserted into the body., which enables precise control and, if necessary, modification of the radiation settings.

So far, the most significant side effect has been the undesired effects on healthy skin and organs. In addition to pain, redness, and swelling, in rare extreme cases also burns have been noticed.

Besides, overheating of the body or larger areas of the body is a significant burden on the cardiovascular system, which unfortunately excludes certain people from this type of therapy. Additional side effects result from the combination with radiotherapy.

Prospects of Success of Hyperthermia Therapy

In many cases, the combination of hyperthermia and radiotherapy can provide better treatment for cancer than radiation alone. Unfortunately, the spectrum of possible tumors that can be treated with this method is not yet fully covered by clinical studies. Besides, only a few tumor centers offer this type of therapy to date.

Where Can Hyperthermia Clinics Be Found in Germany and Switzerland?

To find a suitable hyperthermia clinic, patients should make sure that they contact specialists for radiotherapy. Only experienced doctors can decide whether hyperthermia treatment is advisable in each case. Small practices also offer hyperthermia, but it should be ensured that the doctors treating the patient also evaluate that hyperthermia therapy is advisable. This evaluation is also essential when applying to health insurance companies for reimbursement. The following large hospitals offer hyperthermia treatment in Germany: University Hospital Erlangen, University Hospital Tübingen, University Hospital Düsseldorf, LMU Munich. In Switzerland, under the direction of the Radiooncology Center Aarau, a group of 15 clinics has joined together to form the Swiss Hyperthermia Network (Hyperthermia Network Switzerland) to provide hyperthermia therapy under strictly evidence-based conditions. Throughout Switzerland, patients can be registered on the Swiss Hyperthermia Tumor Board to check whether heat therapy is suitable for their particular case.

Sources:

• www.krebsinformationsdienst.de/behandlung/hyperthermie.php
• www.krebsgesellschaft.de/onko-internetportal/basis-informationen-krebs/therapieformen/hyperthermie-behandlung.html
• Sauer, Rolf (2010): Strahlentherapie und Onkologie. 5., völlig überarb. Aufl. München: Elsevier, Urban & Fischer.
• Richter, Eckart; Bähre, Manfred; Feyerabend, Thomas (2002): Grundlagen der Strahlentherapie. Mit 86 Tabellen. 2., überarb. Aufl. Berlin [u.a.]: Springer.