Heat Therapy Makes High-Risk Soft Tissue Sarcomas More TreatableKey Words
Soft tissue sarcoma, regional hyperthermia therapy. (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary.)
Summary
Patients with high-risk soft tissue sarcomas whose tumors were treated with a kind of localized heat therapy in addition to receiving other treatment lived longer without their disease worsening or returning than did those who did not receive heat therapy.
Source
American Society of Clinical Oncology (ASCO) annual meeting, Chicago, June 4, 2007 (see the meeting abstract).
Background
Cancer can develop in the soft tissues of the body – such as muscle, fat, nerves, blood vessels, or deep layers of the skin. Surgery is the most common treatment for these soft tissue sarcomas, but their location, size, and certain other characteristics make some of these tumors difficult to completely remove. With such “high-grade” tumors there is significant risk the cancer will eventually spread (metastasize) or return (recur).
Nearly half of soft tissue sarcomas are found in the arms and legs. Surgery for such tumors can be successful though amputation is sometimes required. The challenges are usually greater in the 40 percent or so of soft tissue sarcomas found in the chest and abdomen or pelvis, especially when the tumor has high-risk characteristics.
Radiation therapy, delivered before and/or following surgery, is a common treatment to prevent recurrent disease. Other times patients receive neoadjuvant chemotherapy (before surgery) in an effort to shrink the tumor and kill undetectable cancer cells that may have spread.
While not common in the United States, another technique – regional hyperthermia (RH) therapy – has been developed and tested in clinical trials, primarily in Europe. RH heat therapy exposes the body tissue in and around a tumor to high temperatures, as much as 113º Fahrenheit. Not only can such heat kill cancer cells directly, but phase II studies have shown that it appears to make some tumors more susceptible to the effects of chemotherapy, with minimal injury to normal tissue.
The Study
Beginning July 1997 researchers enrolled 341 soft tissue sarcoma patients in this phase III clinical trial from multiple centers in Europe. Eligible patients had one of three high-risk characteristics: their stage II or III primary tumors were larger than 2 inches; the patient’s previously treated disease had recurred; or the patient’s surgery did not remove all detectable disease.
Patients were randomly assigned to one of two groups. In the first group, 172 patients were treated with a combination chemotherapy regimen consisting of etoposide (Lastet®), ifosfamide (Cyfos®), and doxorubicin (Adriamycin®). The second group of 169 patients received the same combination chemotherapy as well as periodic heat treatments to their tumors.
After an initial 12-week round of such therapy, doctors treated some patients in both groups with surgery and/or radiation therapy, as appropriate to their condition. About 60 percent of patients in both groups had their tumors surgically removed, and about 60 percent received radiation treatment. Subsequently, those who could tolerate it received another 12-week round of their assigned experimental treatment: either chemotherapy alone or chemotherapy plus the heat treatment.
The trial (known as the EORTC 6291/ESHO-RHT 95 Intergroup Study) was led by Rolf Issels, M.D., Ph.D., of the University of Munich in Germany, and supported by the European Organization for Research and Treatment of Cancer (EORTC) and the European Society for Hyperthermic Oncology (ESHO).
Results
After a median follow-up of nearly 25 months, patients receiving heat therapy did significantly better by nearly all measures. Their disease-free survival was 16 months, compared to 13 months for those on chemotherapy alone, a 35 percent reduction in risk. Partial and complete tumor responses were seen in 28.7 percent of heat therapy patients, compared to 12.6 percent for those receiving chemotherapy alone.
Patients treated with heat therapy also went an average of 38 months before local progression of disease, compared to 26 months for chemotherapy alone, a 32 percent reduction in risk. Local progression was slower for patients whose tumors were in an arm or leg, but the advantage from heat therapy was about 18 percent, wherever the site of the cancer.
The researchers provided no data at the ASCO meeting on any adverse effects from either the heat therapy or the chemotherapy.
Comments
“The addition of regional hyperthermia improves the response of these soft tissue sarcomas to the standard chemotherapy,” said Barry Anderson, M.D., a senior investigator in the National Cancer Institute’s Cancer Therapy Evaluation Program. “Though we don’t know if these patients will live longer [than those not receiving heat therapy], disease recurrence and local progression are both significantly improved.”
This is an “impressive” study, said Frederick C. Eilber, M.D., of the University of California in Los Angeles during a discussion of the study at the ASCO meeting, partly because it is difficult to recruit large numbers of patients with high-grade soft tissue sarcomas.
Limitations
The fact that so many patients did not receive surgery and/or radiation therapy, and that some patients did not receive the second round of their experimental treatment, makes it difficult to know exactly which patients are most likely to benefit from RH heat therapy, noted Eilber. In addition, Eilber is eager to see how these patients fare over a time frame longer than the two years covered in this study.
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