MIT Lincoln Laboratory radar technology improves breast-cancer treatment  

Clinical study may lead to acceptance of new therapy

A new clinical study of the effectiveness of wide-field focused microwave thermotherapy for shrinking large breast-cancer tumors may pave the way for a cancer treatment that would give women an alternative to mastectomy.

The thermotherapy (heat treatment) approach addresses the limited success of preoperative chemotherapy in shrinking large tumors. A patient with a large breast-cancer tumor often is a candidate only for mastectomy (complete breast removal) unless a preoperative treatment can reduce the tumor to allow physicians to perform a lumpectomy that conserves the breast.

Microwave thermotherapy takes advantage of two facts: heat can increase the effectiveness of chemotherapy, and heat alone can be effective in killing cells containing high amounts of water and ions. Breast-cancer cells typically have a high water and high ion content, while healthy breast tissue is fatty and contain much less water and ions.

"The microwaves, which are delivered by two wide-field applicators placed near the breast, kill the cancerous cells while preserving normal breast tissue by targeting tumor cells containing high amounts of both water and ions," explains Dr. Alan J. Fenn, a senior staff member at Lincoln Laboratory, who developed the concept of focused microwave thermotherapy from adaptive phased-array radar technology used for detecting aircraft and cruise missiles while nullifying enemy jamming. "An adaptive phased array automatically adjusts the timing of multiple antenna elements to form a desired distribution of microwave energy, in this case focused microwave heat energy," says Fenn. "It was a simple move to use this technique to focus microwave energy on cancer cells."

When the microwave energy passes through the tumor, the water molecules vibrate, generating heat through friction. This process eventually raises the cancer cells to a temperature of at least 108°F and kills them, in most cases. The wide-field heat treatment also destroys any microscopic cancer cells in the surrounding healthy tissue.

Treating cancer with heat is not a new idea, but it is difficult to deliver the heat only to cancer cells and not overheat normal tissue, explains Fenn. The focused nature of the thermotherapy helps solves this difficulty. The outpatient procedure uses a single tiny needle probe, placed under ultrasound guidance, to sense and measure parameters during the heat treatment. Previous trials showed that side effects appear to be minimal.

Fifth clinical trial
Since 1999, wide-field focused microwave thermotherapy has been evaluated in four U.S. Food and Drug Administration (FDA)-approved clinical trials for patients with different stages of breast cancer including early-stage and large tumors. The fifth trial started enrolling patients in August 2011 and is a larger FDA-approved phase III randomized study of 238 patients who have large breast-cancer tumors. Patients in the new study will receive either preoperative chemotherapy alone or preoperative chemotherapy combined with microwave heat treatments at a participating medical center. Two clinical sites are enrolling patients in the current study, the University of Oklahoma Breast Institute in Oklahoma City and the Comprehensive Breast Center of Coral Springs, Florida, a division of 21st Century Oncology.

"We are hoping that we can achieve faster and more complete responses of large breast cancers to chemotherapy by adding the microwave treatments. If we kill a tumor faster, we might theoretically also be aiding the body's ability to immunologically detect and destroy additional tumor cells elsewhere," says Dr. William C. Dooley, principal investigator in the trials at the Breast Institute. "A more long-term idea is that if this focused microwave treatment procedure shrinks tumors faster, can we use fewer chemo treatments or lower doses and be just as effective?”

Another important objective is to demonstrate that the combined treatments of heat and chemotherapy can reduce the rate of mastectomy. The need for breast-cancer treatment options is strong. The National Cancer Institute estimates that 230,480 women and 2100 men will be diagnosed with breast cancer in 2011, 53,000 more cases than were diagnosed just four years ago.

"If the trial confirms our prior work, we would anticipate FDA approval and then the technology could become available for treating large tumors in the breast at hospitals having such resources," says Dooley.

thermochemotherapy results chartThe chart shows a comparison of breast-tumor volume reduction for a subset of cases from the 2002–2004 clinical trials. The tumor volumes were based on ultrasound measurement for patients treated in the two arms of the randomized focused microwave thermochemotherapy (heat + chemotherapy) versus chemotherapy study. As can be seen from the chart above, 3 tumors were virtually eradicated by using thermochemotherapy, and the other 6 were significantly decreased; post treatment lumpectomy, therefore, would have a very good chance of excising all the cancer. The new study is being undertaken to replicate these results in a larger patient population, thereby advancing the FDA approval of thermochemotherapy for use in hospitals.


Past trials
Results from past trials demonstrated that thermotherapy holds significant promise for improved breast-cancer treatment. A study published in the journal Cancer Therapy in 2007 reported that using the heat treatment significantly increased the effectiveness of chemotherapy for a small group of patients with large breast tumors. In the trials reported on in this study, large tumors treated with a combination of chemotherapy and focused microwave heat shrunk nearly 50 percent more than tumors treated with chemotherapy alone. Fenn and Dooley co-authored this study with the other principal investigators involved in the clinical trial that ran from November 2002 to May 2004: Dr. Hernan I. Vargas, Harbor-UCLA Medical Center; Dr. Mary Beth Tomaselli, Comprehensive Breast Center, Coral Springs; and Dr. Jay K. Harness, St. Joseph’s Hospital in Orange, California. A complete review of past clinical trials for focused microwave treatment of breast cancer can be found in an MIT open-access DSpace web site article, which was published in the Annals of Surgical Oncology in 2010.

The focused microwave heat treatment is also documented in a book authored by Fenn, Adaptive Phased Array Thermotherapy for Cancer (Artech House, 2009), which describes this novel heat treatment approach using adaptively focused microwaves for killing cancer cells in the body. "The approach could also be applied to the treatment of cancers other than breast cancer, such as prostate, liver, lung, and benign breast conditions including pre-cancerous tumors," says Fenn.

The U. S. Air Force funded the Lincoln Laboratory spaceborne phased-array radar research that was applied as a dual-use technology for cancer treatment. Medifocus, Inc. licenses the focused microwave thermotherapy technology from MIT, has produced the clinical systems to perform the procedures, and funds the clinical studies, including the current phase III study.

Posted January 2012

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