Another consequence of inadequate blood supply is reduced

Hyperthermia is well suited for a wide variety of tumour

oxygen. Radiation is more effective in destroying well-

locations, including chest wall, axilla, head & neck, breast,

oxygenated cells while hyperthermia destroys cells lacking

groin, and all tumours located directly on or under the skin. It

oxygen. When the treatments are used together, both types of

has also been used to reduce the size of tumours prior to

cells can be destroyed. Cancer cells are also more vulnerable

surgery, increasing the likelihood of successful removal of

to heat because of insufficient nutrition and a greater acidity. In

cancerous tissue. The use of local hyperthermia is limited to

addition, heated cells are often more permeable to the drugs

solid tumour cancer. Blood diseases (like leukemia) and certain

used in chemotherapy.

tumour locations within the body (lung cancer, for example) are

difficult to heat.

Hyperthermia, when used correctly, has minimal side effects, in

contrast to the recognized side effects of radiation and

I hope the therapists amongst us who are involved in oncology

and PNI can make good use of this information, as I feel sure

that this is a treatment that will be available on the NHS or

Originally, hyperthermia techniques involved heating the entire

privately in the UK in the foreseeable future.

body. In the late 1800's several doctors reported complete

disappearance of tumours in some patients who had cancer

and who had also developed high fevers in reaction to other

infections. Since that time, several methods of heating the

entire body have evolved, including the artificial induction of

fever, the wrapping of an anaesthetized patient in plastic and

dipping them in hot wax, and heating the blood supply.

However, many undesirable side effects are associated with

whole body heating. This has led research efforts towards more

localized and precise application, control and measurement of

Microwave: Heat produced by microwaves can be directed at

tumours that are 1-3 cm from the surface of the skin.

Microwaves are rapidly absorbed as they penetrate deeper into

the body. Thus, tumours located at depths greater than 3 cm

from the surface of the body cannot be effectively heated with

presently used microwave techniques.

Interstitial Radiofrequency: Interstitial treatments send RF

energy through small needles placed into the tumour. After

heating, interstitial radioactive therapy material can be

introduced into the tumour site through the same probes used

to introduce heat (this is called brachytherapy and has been

used as a cancer treatment for many years). Interstitial

hyperthermia can also be used with external beam radiation.

This technique allows greater control of heat application, but is

an invasive procedure (the placement of needles can be painful

and restricts the movement of the patient).

Ultrasound: This technique uses ultra-high frequency

soundwaves to produce heat within the tumour. Ultrasound is

more easily focused than other energy modalities and can be

applied to tumours located from the skin to 8 cm within the

body. This allows the treatment of tumours unreachable by

other external modalities.

There is no "best" hyperthermia method. Microwave,

radiofrequency, and ultrasound treatments are appropriate in

different situations. It is more difficult to direct and focus

microwave and radiofrequency energy. This sometimes results

in the heating and damaging of normal cells. Ultrasound is

more easily focused, which eliminates these problems. Also,

ultrasound can be used for tumours at those deeper locations

which microwave and radiofrequency cannot reach. On the

other hand, ultrasound is not appropriate for most tumours

involving bone or behind gas-filled cavities, such as bowel or

lung. In these situations, microwaves would be more useful.

However, with increasing control of application, ultrasound can

be used for tumours located closer and closer to bone.