Intraoperative Radiation Therapy

Overview

Enlarge

Intraoperative radiation therapy (IORT) delivers a concentrated beam of radiation to cancerous tumors while they are exposed during surgery. This technique allows doctors to administer high doses of radiation to tumors without exposing nearby healthy organs to radiation. A single dose of intraoperative radiation may have as much effect on the tumor as 10-20 daily radiation treatments. The form of IORT most commonly used at Mayo Clinic also is called intraoperative electron radiation therapy, or IOERT.

Mayo Clinic's IORT program, begun in 1981, is one of the world's largest. More than 1,700 patients have received this treatment at Mayo Clinic in Minnesota, and 100+ in Arizona. This extensive experience with IORT has helped Mayo Clinic physicians develop exceptional skill. The IORT team at Mayo Clinic includes specialists in radiation oncology who perform the procedure, surgery, anesthesiology and pathology.

Conditions Treated with IORT

IORT is effective for tumors that cannot be completely removed surgically because they are either attached or close to healthy tissue that cannot be removed. Recurrent rectal cancer is the most common disease treated this way at Mayo Clinic. IORT also is used for recurrent gynecologic, genitourinary, and gastrointestinal cancers as well as primary locally advanced cancers with a low likelihood of cure with surgery alone. IORT is also used to treat soft tissue sarcomas and cancers that recur in lymph nodes. For patients who have cancer that has come back at the original site and for patients who have locally advanced cancers, IORT can be an effective addition in achieving long-term tumor control.

How It Works

IORT is almost always used in conjunction with external radiation given prior to surgery. During surgery, after the surgeon has removed as much of the tumor as possible, a machine called a linear accelerator delivers a concentrated beam of electron radiation directly to the exposed cancerous tumors. IORT may be used when the remaining tumor is microscopic and not visible to the eye.

The surgeon moves healthy organs out of the radiation field to prevent damage, and special tubes are used to focus the beams safely on the tumor or the tumor bed. Mayo Clinic in Minnesota has a dedicated linear accelerator placed in a special lead-lined operating room to deliver IORT. In Arizona, Mayo Clinic is one of only a few institutions in the United States that uses a Mobetron, an FDA-approved mobile linear accelerator that can be brought to the operating room.

Results of IORT

Recent studies at Mayo Clinic in Minnesota show that patients who have locally advanced primary colon or rectal cancer who received IORT as a component of their treatment had a five-year survival rate, compared to 24 percent in the control group without IORT. The study also found that patients with locally recurrent colon or rectal cancer who received IORT had a 19 percent five-year survival rate, compared to only 7 percent for patients who did not receive IORT.

Mayo Clinic studies of locally recurrent gynecologic and genitourinary cancers and abdominal-pelvis sarcomas show that 25 to 40 percent of patients who received IORT as a component of treatment were five-year survivors. Many institutions do not offer curative treatment options for patients with locally recurrent cancers.

• Treatment in Arizona
• Treatment in Minnesota