Hyperthermia

What is hyperthermia?

Hyperthermia is a treatment method involving the controlled heating of tumour tissues to temperatures typically between 39°C and 45°C for one hour.

This targeted heat therapy works to damage cancer cells directly, but its primary role is enhancing the effectiveness of radiotherapy and chemotherapy.

At moderate temperatures, hyperthermia sensitises tumour cells to radiation and chemotherapy by altering the tumour's microenvironment, improving oxygenation, and inhibiting DNA repair mechanisms.

Clinical studies demonstrate that hyperthermia can significantly increase treatment response rates without adding toxicity when carefully applied, as it affects tumour cells more than surrounding healthy tissues.

How it works

Hyperthermia works by applying controlled heat to tumour tissues. This process primarily enhances the effectiveness of other cancer treatments like radiotherapy and chemotherapy, increasing the likelihood of tumour cell death. The heat affects cancer cells in several ways:

• Sensitising cells to radiation and chemotherapy: Heat can make cancer cells more susceptible to damage from radiation and chemotherapy by disrupting cellular repair mechanisms, particularly for DNA. More cells are killed with the same dose of radiotherapy. It also increases the cells' response to treatment by reducing their ability to repair the damage caused by these therapies.

• Improving blood flow and oxygenation: Hyperthermia improves blood flow within the tumour, which increases oxygen levels. Tumours often have low oxygen levels (hypoxia), making them less responsive to radiation. By enhancing oxygenation, hyperthermia makes radiation more effective.

• Direct thermal damage: At higher sustained temperatures, hyperthermia can directly damage or kill cancer cells by disrupting their structural proteins and cellular functions. This effect is particularly

Why do you need hyperthermia?

Hyperthermia therapy can be particularly beneficial for several types of cancers and certain treatment-resistant or recurrent tumours.

Conditions that may benefit include:

• Superficial tumours: Cancers close to the skin's surface, such as melanoma, recurrent breast cancer, and head and neck cancers, respond well to hyperthermia because these tumours are easily accessible for localized heat application.

• Deep-seated tumours: Hyperthermia can also target deeper tumours when combined with other treatments. Cancers of the cervix, bladder, rectum, and prostate can benefit, especially when hyperthermia is used with radiotherapy to enhance treatment effects.

• Recurrent tumours: Hyperthermia is often effective in cases where cancer recurs in a previously treated area. Radiation doses are limited in repeat treatments due to the risk of damaging surrounding healthy tissue, but adding hyperthermia can help overcome this challenge by enhancing the effects of radiation at lower doses.

• Tumours with hypoxic or resistant cells: Cancers with hypoxic (low-oxygen) cells are typically more resistant to radiation. Hyperthermia improves blood flow and oxygenation in the tumour, making these cells more sensitive to radiation.

• Soft tissue sarcomas: Hyperthermia has shown success in treating certain soft tissue sarcomas, especially when combined with radiation or chemotherapy.

• Advanced or unresectable tumours: In cases where tumours are inoperable due to size, location, or stage, hyperthermia can help to control tumour growth, reduce symptoms, and potentially improve overall treatment outcomes when used as an adjunct therapy.

Research is ongoing, and the use of hyperthermia in combination with immunotherapy and other advanced treatments is showing promise in expanding its potential applications.

Why should not undergo hyperthermia?

While hyperthermia is a promising adjunct therapy for many cancers, certain individuals may not be suitable candidates. Contraindications and precautions include:

• Patients with metal implants: Metal implants, like joint replacements or pacemakers, can absorb heat and make it difficult to control the temperature during hyperthermia therapy. This could lead to overheating in the surrounding tissue, potentially causing burns or tissue damage.

• Patients with cardiovascular or respiratory issues: Those with serious heart or lung conditions may have difficulty tolerating the increased body temperature and blood flow associated with hyperthermia. In these cases, the stress of treatment might outweigh the benefits.

• Pregnant individuals: Due to potential risks to the fetus from increased body temperatures, hyperthermia is generally avoided during pregnancy.

• Patients with certain autoimmune diseases: Conditions such as systemic lupus erythematosus (SLE) can make patients more susceptible to tissue damage or immune system reactions, which may be exacerbated by heat.

• Compromised skin integrity: For those with extensive skin wounds or burns, applying heat directly may worsen the injury or lead to infection. Hyperthermia may be avoided or adjusted based on skin health and wound location.

• Patients unable to tolerate elevated temperatures: Some people are more sensitive to heat due to individual tolerance or specific conditions, which could increase the risk of side effects.

What are the risks and complications of hyperthermia?

Hyperthermia therapy, while generally well-tolerated, does carry some risks and potential complications. These can vary based on the treatment area, temperature, and the patient’s overall health.

Some risks and complications include:

• Skin burns: Overheating the skin or tissues near the treatment area can cause burns, especially in superficial hyperthermia where heat is applied closer to the skin.

• Pain or discomfort: Some patients may feel mild to moderate pain or discomfort in the treated area, particularly if the temperature is difficult to control or maintain evenly. This can include a sensation of warmth or even mild tenderness after treatment.

• Fatigue and malaise: General tiredness or feeling unwell is a possible side effect due to the body's reaction to the heat, especially in whole body hyperthermia treatments.

• Local sensitivity and pigmentation changes: Some patients may experience sensitivity in the treated area or temporary skin color changes. These changes are usually temporary but can sometimes last for several weeks post-treatment.

Close monitoring and precise temperature control are key to minimising these risks. Hyperthermia treatments are often adapted to each patient's tolerance, with lower temperatures used if needed to reduce side effects.

Your doctor would be able to discuss detailed specific side effects specific to your condition.

What can you expect during hyperthermia?

Before the procedure

A nurse or radiation therapist will explain the treatment to you, how long it will take, and what you need to do. This ensures you know what to expect.

You will be placed on the treatment couch in the same position as during your simulation. This helps the team be sure the setup is exactly right.

A nurse will check and record your vital signs (like your blood pressure and heart rate) to make sure you're stable before starting.

For superficial hyperthermia, a special transparent template will be placed on the area that needs treatment. This template helps guide the placement of temperature sensors and ensures the treatment area stays consistent.

For deep hyperthermia, a catheter may be inserted in the body, with sensors placed inside it for internal temperature monitoring.

During the procedure

• Optimising the treatment: During the treatment, the team ensures that the radiofrequency energy is properly coupled with your body and selects the best settings to raise the temperature in the target area effectively.

• Starting the pre-heating stage: Once the pre-treatment setup is complete, the therapist asks you to remain still and to let them know if you experience any pain during the process. A radiation oncologist will also review the setup and treatment parameters before the treatment begins.

• Staying still and monitoring: As the treatment starts, the radiation therapist will closely monitor your response, adjusting the settings as needed to reach the desired temperature and treatment goal.

  Your vital signs are checked again about midway through the treatment by a nurse, with all adjustments and observations recorded in the treatment software.

After the procedure

Once the treatment is finished, a nurse will take and record your final vital signs. The antenna and the template (with the attached sensors) are carefully removed from your body.

A radiation therapist will help you off the treatment couch and accompany you out of the room. If there is a review appointment on the same day, you will meet with the radiation oncologist; if not, you will be reminded of your next scheduled appointment.

Care and recovery after hyperthermia

During hyperthermia treatment, patients can expect the following experiences and effects:

• Sensation of warmth: Patients often feel warmth or heat in the targeted area. This sensation is usually mild but can vary depending on the treatment area, depth, and duration. The medical team carefully monitors the temperature to prevent discomfort or excessive heat.

• Possible mild discomfort: Some patients may feel minor discomfort in the heated area. In cases of superficial hyperthermia, the skin might feel warm or slightly flushed. Deep hyperthermia may sometimes cause a feeling of pressure or warmth within the body.

• Duration of treatment: Sessions usually last between 60 – 90 minutes, depending on the treatment plan. Patients are encouraged to remain as relaxed during this time.

• Body positioning and support: To ensure comfort, the patient is positioned carefully with pillows or supports. Some hyperthermia machines may require the patient to be in a specific position, depending on the area being treated.

• Monitoring by the medical team: Temperature probes or thermometers may be used to monitor the skin or the treatment area, ensuring the heat stays within a safe and therapeutic range. Vital signs may also be regularly checked during and after treatment.

• Potential skin reactions: Mild redness, tenderness, or swelling at the application site can sometimes occur, particularly with superficial hyperthermia. These effects are generally temporary and subside shortly after the session.

• Aftereffects and mild fatigue: Patients may feel a bit tired after hyperthermia treatment, as the body expends energy in response to the heat. This fatigue is usually mild and improves with rest.

• Cooling or hydration needs: The treatment room may be kept at a comfortable temperature, and patients are encouraged to stay hydrated before and after treatment to prevent dehydration.

Throughout the session, you can communicate with the care team to ensure your comfort, and any concerns or discomfort can be addressed promptly.