Heat Shown to Augment Radiation Therapy

Heating tumors before radiation therapy has been shown to shrink tumors entirely in more patients with recurrent cancer than radiation alone, according to a new study.

In a study of 109 patients, scientists from Duke University Comprehensive Cancer Center (Durham, NC, USA) discovered that the combined treatment shrank tumors entirely in 66% of patients with tumors in the chest wall, breast, head, neck, and skin. In contrast, radiation used alone resulted in total tumor shrinkage in 42% of patients. The researchers reported that these results clearly show that hyperthermia plus radiation should be the new standard of care for these women.

"The dual therapy offers the best potential for long-term cancer control in women whose cancer has recurred in their chest wall but has not spread elsewhere in the body,” remarked Ellen Jones, M.D., Ph.D., a Duke radiation oncologist and chief investigator of the study, which was published in the May 1, 2005, issue of the Journal of Clinical Oncology.

Individuals with recurrent cancer have a poor prognosis because the cancer is frequently aggressive and because a full dose of radiation is too toxic the second time, according to Dr. Jones. Therefore, searching for newer methods to improve the effectiveness of radiation is crucial to enhancing the patient's quality of life and possibly extending survival, she said.

Hyperthermia was even more effective among individuals who had undergone radiation to treat their primary tumor, the scientists discovered. Among these individuals, 68% had complete tumor shrinkage following the dual therapy vs 23% of patients who were receiving radiation for the first time. Overall, the combined therapy did not increase survival for the patients in the study, mainly because so many patients had metastases elsewhere in the body, according to the researchers. Dr. Jones observed, however, that hypothermia improved local tumor control in the area of recurrence.

Hyperthermia utilizes microwave energy to increase the temperature of the tumor, activating a series of complete physiologic processes that are crucial to the tumor's destruction, according to the investigators. A tumor's blood vessels are more apt to leak than normal blood vessels, and heat opens vessel walls to an even greater degree, enabling radiation and chemotherapy to infiltrate more effectively and sensitizing cells to radiation.

Whereas hypothermia has been assessed in combination with chemotherapy and radiation in many studies worldwide, those studies have generated conflicting data, according to the researchers. This study provides clinicians with a "verifiable prescription” for hypothermia with clear-cut dosing and temperature recommendations, according to Dr. Jones.