updated 10/11/2005 11:54:18 AM ET 2005-10-11T15:54:18

The tumors looked like five large mosquito bites dotting Alison Williams’ chest. The cancer that already had cost her breasts was back again, this time in the wall of her chest, an ominously hard-to-treat spot.

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Her doctor tried an experiment, beaming microwaves onto Williams’ chest to heat it to about 109 degrees. The hope: that the heat would help radiation treatment attack the tumors — and they disappeared.

Scientists have long thought that simple heat could increase the effectiveness of some cancer therapies. But just how much to cook the tumor, and which cancers are susceptible, have stymied the field. Now, backed by tantalizing new evidence, a growing number of studies are enrolling patients in hopes of finally settling whether it’s time to turn up the heat.

“We need to keep pushing ahead on this,” says Dr. Ellen Jones of Duke University, who recently published research that showed heat significantly helped patients like Williams and has a major study under way to test its effects against cervical cancer as well.

Hyperthermia involves gradually raising the temperature of cancer-riddled tissue to anywhere from 105 to 113 degrees — not enough to burn, but like there’s a high fever in that body part. There are different methods: beaming microwaves or ultrasound onto tumors near the skin’s surface, inserting probes that emit microwaves or radio waves into the tumor itself or the affected organ, or even using a giant heating machine to raise the entire body temperature.

Here’s the quandary: Some studies have found hyperthermia could help certain patients with breast, cervical, head and neck cancers or melanoma. But others show no effect.

Jones, a radiation oncologist, thinks the problem is in consistently getting the tumor’s temperature high enough, for long enough.

“The body does not want to be heated. It fights the heating process,” agrees William Straube, a physicist at Washington University in St. Louis, which, like Duke, has a major research program on cancer hyperthermia.

Jones set out to determine a prescription-level dose of heat, inserting temperature probes to prove the degree. She gave more than 100 patients with recurrent, incurable cancer — mostly painful breast cancer sores on the chest wall — either radiation alone or radiation plus a microwave-laden water bath on the tumor site.

Among women who had previously undergone radiation, only 23 percent had their tumors disappear with a second round — compared with 68 percent who underwent heat plus radiation.

The study, reported in May’s Journal of Clinical Oncology, didn’t show that hyperthermia helped patients live longer; most also had cancer in parts of the body not heated.

But last month, Jones and researchers from Norway and the Netherlands reported a study of 68 patients with advanced cervical cancer that found adding heat to standard radiation and chemotherapy yielded an 84 percent survival rate, better than expected. They now are enrolling 400 cervical cancer patients in a Phase III study to try to prove hyperthermia’s effect.

Why would heat work? It’s thought to kill some cancer cells directly and help chemotherapy better penetrate certain tumors by dilating blood vessels.

But mostly it’s done to render the cancer more vulnerable to radiation. Heat increases the amount of oxygen inside cells. Oxygen-starved cells are more resistant to radiation damage, and tumor cells contain less oxygen than healthy tissue.

That’s of particular interest for patients with recurrent cancer, because they can tolerate only so many rounds before radiation damages, even destroys, healthy tissue or bone surrounding the cancer.

Much work must still be done to prove heat really works, cautions Dr. Len Lichtenfeld of the American Cancer Society.

The National Cancer Institute funded more than $19 million in hyperthermia research last year to explore the outstanding questions; half a dozen clinical trials involving a variety of heat treatments are under way.

“If it breaks out again, we’ll just do it again,” says Williams, the Raleigh, N.C., woman who had two separate batches of chest-wall tumors zapped with heat and radiation. While she has cancer elsewhere in her body, a year later none of the heat-treated tumors has returned. “I’m tickled pink.”

© 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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