Intra-Operative Radiation Therapy

As more women with early stages of breast cancer are choosing treatment with breast conserving therapy—lumpectomy (surgery to remove a breast lump)—radiation therapy is also becoming more commonly used to help destroy any remaining cancer cells after surgery. Currently, most lumpectomy patients undergo six to seven weeks of radiation therapy following recovery from their surgery. A new type of radiation technology is being developed to lessen the amount of time women must undergo radiation therapy. Intra-operative radiation involves giving patients a "boost" of radiation therapy during breast cancer surgery. If clinical trials prove its effectiveness, the new treatment may eliminate the need for weeks of post-operative radiation treatment.

What is Intra-Operative Radiation Therapy?

Intra-operative radiation therapy (or IORT) is a single "boost" of radiation therapy that is delivered directly to the area of the breast where the tumor was removed. The radiation "boost" is administered immediately after a lumpectomy is performed, while the patient is still under general anesthesia. Patients are either treated with a miniature portable radiation therapy system in the operation room or transferred to the radiation department within the hospital where they receive the radiation "boost."

Intra-operative radiation therapy allows physicians to give patients higher doses of radiation than standard external beam radiation therapy. External beam radiation therapy involves administering radiation over a period of six weeks or more following breast cancer surgery. A weak amount of radiation dosage is used during external beam radiotherapy to keep from damaging healthy, non-cancerous tissue which is penetrated as the radiation travels to the cancer site. External radiotherapy must be repeated over several sessions to deliver an accumulated dose sufficient to destroy the cancer cells. With intra-operative radiation therapy, the cancerous target area is already directly exposed, allowing the physician to administer a one-time boost of high energy radiation directly to the tumor site.

Clinical Studies on Intra-Operative Radiation Therapy

The Medical College of Ohio and the Centre Regional de Lutte Contre le Cancer in Montepellier, France, studied 72 breast cancer patients between the ages of 33 and 81. All patients had been diagnosed with Stage I, Stage IIA, or Stage IIB breast cancer and were treated with lumpectomies followed by intra-operative radiation therapy. Each patient was followed for up to 14 years after treatment. Of the 72 patients, 100% achieved local control of the cancer and 98.6% became disease-free.

Intra-operative radiation therapy did lengthen the patients' surgeries by 30 to 35 minutes, though IORT eliminated the need for weeks of radiation therapy after surgery. According to Ralph R. Dobelbower, MD, PhD of the Medical College of Ohio, no significant complications developed as a result of intra-operative radiation during the study. Cosmetic results were considered excellent by both the researchers and the patients. However, according to Dr. Dobelbower, approximately 10% of the patients developed palpable (able to be felt) plaque-like hardening at the lumpectomy site. These forms disappeared after several months.

Photoelectron Corporation just received permission to begin a clinical study on intra-operative radiation with their miniature radiation therapy machine. The study will be conducted at Middlesex Hospital in London, England, but medical centers in the United States and other European countries are also expected to participate. Surgery Professor Michael Baum of Middlesex Hospital believes the Photon Radiosurgery System (PRS) that will be used in the study shows promise. Conservative treatment of breast cancer (lumpectomy) may not require radiation therapy that involves the entire breast, said Baum in a Photoelectron Corporation press release. Based on his previous research, Baum said that delivering targeted intra-operative radiation therapy has proven to be safe and feasible.

Intra-operative radiation therapy has also been used in studies on patients with other types of cancers including bladder, bone, brain, cervical, colon, lung, prostate, and stomach cancers. Clinical studies are currently underway to test the effectiveness of intra-operative radiation therapy on these and other types of cancer tumors.

Possible Benefits to Intra-Operative Radiation Therapy for Breast Cancer Patients

• No delay between surgery and radiation therapy (currently, patients wait approximately one month after surgery before beginning radiation therapy).
• Significant reduction in the amount of time a woman must undergo radiation therapy since the radiation boost is given during the lumpectomy operation. Currently, many women who have lumpectomies must re-arrange their schedules and often travel far distances to receive radiation treatment sessions.
• Provides a higher dose of radiation directly to the tumor site.
• Minimizes the possibility of missing the tumor area because the radiation boost is given during surgery when the tumor area is visible.
• Minimizes radiation to normal breast tissue.
• Treatment may be less costly.

Additional References and Resources

• Intraop Medical, Inc. is responsible for the design of the Mobetron radiation system and provides information on intra-operative radiation therapy at http://www.intraopmedical.com/
• The March 9, 2000 news report, "Study Tests Effectiveness of Radiation Therapy During Breast Cancer Surgery," is available at http://www.imaginis.com/breasthealth/news/news3.09.00b.asp
• To learn more about radiation therapy for the treatment of breast cancer, please visit http://www.imaginis.com/breasthealth/radio_bctreatment.asp
• Visit the Medical College of Ohio website at http://www.mco.edu

Updated: September 12, 2007