About Breast Cancer>Treatments>Radiation therapy for breast cancer > Intraoperative radiation therapy (IORT) breast cancer treatment

Intraoperative radiation therapy (IORT) breast cancer treatment


Intraoperative radiation therapy, or IORT, is a type of radiation therapy given during lumpectomy surgery to remove only the breast cancer tumor. While the lumpectomy incision is still open, doctors use a special device to deliver one large dose of radiation directly to the tumor site (the “tumor bed”) to treat any cancer cells that may remain after the tumor is removed.

IORT is different from external beam radiation therapy (EBRT), which treats the entire breast in multiple doses over a several-week period. IORT treats a specific area and is given in a single dose.

IORT is not available at many hospitals. One reason is that IORT requires an operating room that is shielded from radiation. Many hospitals do not have this technology. It can also be challenging to schedule the extra healthcare professionals required to perform radiation at the same time as surgery.

While you might be able to find treatment with IORT at your cancer center, some experts feel it should not be used in place of EBRT. In fact, the American Brachytherapy Society recommends it only be done in clinical trials, because so much is unknown about its effectiveness at treating breast cancer.


What are the benefits of IORT?

IORT can offer these benefits:

  • Convenience: Traditional radiation therapy often requires daily treatments over an average of 6 weeks. IORT offers a single dose of one-time radiation treatment.
  • Lower cost: Since IORT requires only a single dose of radiation, it’s much less expensive than traditional radiation therapy.
  • Less radiation is delivered to healthy tissue: With IORT, nearby healthy tissue and organs are less exposed to radiation than they would be with EBRT.

After lumpectomy with IORT, your doctors will test the area of tissue around the tumor, called the tumor margin, and the nearby lymph nodes, for cancer cells. If the tests show there are cancer cells in the tumor margins or lymph nodes, EBRT may still be recommended to lower the risk of recurrence.


How do I know if I’m a candidate for IORT?

You may be a candidate for IORT if:

  • you were diagnosed with an early-stage breast cancer
  • your lymph nodes test negative for cancer cells
  • the tumor is small (in one trial, most tumors being treated measured up to 2 cm; in another trial, tumors were up to 2.5 cm)
  • you are over age 50

IORT is not generally recommended for women under the age of 50 because long-term post-treatment issues in this group are not yet fully understood.


What should I expect from the IORT procedure?

If IORT has been recommended for you, you’ll likely be taken through the following steps:

  • You will be put under anesthesia in the operating room.
  • While you are asleep, your surgeon will perform the lumpectomy, by making an incision in your breast and removing the tumor.
  • Once the tumor is removed, your doctor will place the applicator of the IORT device directly into the opening where the tumor was (the “tumor bed”).
  • Through the applicator, a dose of radiation will be delivered directly to the tumor bed. The treatment can take about 30 minutes.
  • Your surgeon will then close the incision.

What are the side effects & risks of IORT?

The main side effects of IORT are temporary bruising and potential buildup of fluid in the breast tissue.

It’s important to know that people treated with IORT have a higher risk of recurrence in the same breast than people treated with EBRT. However, breast cancer survival rates for both types of radiation therapy are about the same.


IORT prognosis

Two large studies, both published in 2013, looked at the effectiveness of IORT versus EBRT in women with early-stage breast cancer:

  • The TARGIT-A study: Risk-adapted targeted intraoperative radiotherapy versus whole-breast radiotherapy for breast cancer: 5-year results for local control and overall survival from the TARGIT-A randomized trial
  • The ELIOT study: Intraoperative radiotherapy versus external radiotherapy for early breast cancer (ELIOT): randomised controlled equivalence trial

Results from both studies showed that when IORT effectiveness was compared with EBRT effectiveness in these women, breast cancer survival rates and overall survival rates were about the same.

In the TARGIT-A study, about 5 years after IORT or EBRT treatment, results showed

  • the women treated with IORT had breast cancer survival rates of 97.4%
  • the women treated with EBRT had breast cancer survival rates of 98.1%

Results from the ELIOT study showed that about 6 years after IORT or EBRT treatment

  • the women treated with IORT had breast cancer survival rates of 96.8%
  • the women treated with EBRT had breast cancer survival rates of 96.9%

It’s important to know that women in the ELIOT study receiving IORT were found to have higher rates of breast cancer recurrence in the same breast than the women receiving EBRT. But as mentioned above, overall survival was about the same despite these recurrences.

Doctors agree that more research and longer follow-up data are needed before we have a clearer picture of the safety and effectiveness of IORT in treating breast cancer.


Related resources


Reviewed and updated: January 14, 2022

Reviewed by: Neil K. Taunk, MD, MSCTS


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