Hyperthermia is a type of cancer treatment that involves heating the body in order to damage cancer cells without harming the normal tissues. It can both destroy cancer cells and shrink tumors, and is well known to enhance the therapeutic ratio of radiotherapy and chemotherapy, and it has become the fifth major therapy in tumor treatment. It has the ability to widely affect the metabolism of multiple substances to treat tumors, as opposed to drugs that can only regulate the metabolism of a single substance and cannot maximize the therapeutic effect.
Because tumor cells are less resilient to heat than normal cells are, increasing the temperature inside the tumor can induce cell death and inhibit DNA repair. Hyperthermia significantly alters multiple components of glycolysis and mitochondrial function in almost all tumor cell lines. Hyperthermia therapy is usually used in combination with other therapies, whether conventional or more holistic.
Types of hyperthermia therapy:
- Local hyperthermia therapy uses external energy sources such as microwave, radiofrequency, infrared devices, or ultrasound to heat the tumor area.
- Regional hyperthermia therapy is applied to larger areas of the body, such as an organ or whole limb.
- Whole-body hyperthermia heats the entire body, and can be used to treat metastatic cancer.
Types of cancers treated with hyperthermia therapy:
- -appendix cancer
- -bladder
- -brain cancer
- -breast
- -cervical cancer
- -esophageal cancer
- -head and neck cancer
- -liver cancer
- -lung cancer
- -melanoma
- -mesothelioma
- -sarcoma
- -rectal cancer
One study explored the effects of a single trial of whole body hyperthermia (WBH) alone, or in combination with glucose on the growth of spontaneous mammary tumors in mice. A single intraperitoneal injection of glucose had no effect, but whole body hyperthermia alone and a glucose injection 30 minutes before the whole body hyperthermia significantly inhibited the tumor growth. A combined treatment with glucose and whole body hyperthermia suppressed the tumor growth almost completely for 7 days. Glucose increases the blood viscosity and reduces the tumour blood flow, resulting in a decrease of tumour cell activity and blood flow, allowing the whole body hyperthermia to then induce cell death.
Mechanisms of action
- Hyperthermia Induces the DNA Damage Response and Inhibits Repair Mechanisms in Tumors.
Under heat stress, increases in ROS and other free radicals have been observed in cells. This affects the integrity of the mitochondria, which is an important contributor to the redox status of the cell and leads to DNA damage.
The tumoral DNA damage begins to accumulate under the heat therapy as repair pathways malfunction, causing the formation of tumor neoantigens specific to cancer cells (which helps the body mount an immune response against the cancer.)
- Hyperthermia Induces Immunogenic Cell Death through HSP Release, ER Stress, and ROS
Hyperthermia induces two types of Immunogenic Cell Death (ICD). The first (type I ICD) is the result of collateral stress effects on the endoplasmic reticulum (ER) and is constituted by effectors that mainly target cytosolic proteins, membrane channels, or other cellular components that can indirectly impact the ER. The second (type II ICD) is established by mechanisms primarily targeting the ER itself and causing stress. Both types of ICD elicit an adaptive immune response.
- Hyperthermia Enhances Immune Cell Trafficking and the Immune Response
Hyperthermia exerts direct effects on immune cell trafficking, (which is an important process for maintaining homeostasis and initiating immune response.) Hyperthermia also inhibits immunosuppressive tolerogenic signals, promoting the maturation of several types of antigen-presenting cells and stimulating the release of inflammatory factors to help destroy the tumor.
- Hyperthermia Alleviates Immunosuppressive Hypoxia
Hyperthermia therapy can improve the oxygenation status of a tumor, which can alleviate the immunosuppressive hypoxic (insufficient oxygen) environment. The heat activates certain thermoregulatory responses, causing the arterioles to dilate, increasing blood flow and decreasing hypoxia. This facilitates trafficking of immune cells and therapeutic agents.
Who may benefit most from hyperthermia therapy?
- Those with deep tumors that surgery can’t treat.
- Those with health conditions that prevent them from having surgery.
- Those with small tumors near the surface of your skin.
- Those with tumors in a body cavity.