Breast Cancer: Intraoperative Radiation Therapy (IORT)


Intraoperative radiation therapy (IORT) is a specialized form of radiation treatment administered during lumpectomy surgery, targeting the tumor site directly. After the breast cancer tumor is removed and while the lumpectomy incision remains open, a special device delivers a single large dose of radiation to the “tumor bed” to eliminate any residual cancer cells. This approach contrasts with external beam radiation therapy (EBRT), which involves treating the entire breast with multiple doses over several weeks.

The availability of IORT is limited due to the specific requirements it entails. Hospitals must have operating rooms that are properly shielded from radiation, a technology not widely available. Additionally, coordinating the presence of the necessary healthcare professionals to perform radiation therapy simultaneously with surgery poses significant logistical challenges.

Despite its potential, IORT is viewed with caution by some in the medical community. The American Brachytherapy Society, for instance, advises that IORT should be reserved for clinical trials because of the limited understanding of its long-term effectiveness in treating breast cancer. This recommendation reflects a broader hesitance to replace the established EBRT with IORT outside of controlled research settings.

Reasons for undergoing the procedure

You may be a candidate for IORT if:

  • You were diagnosed with 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.


It’s crucial to note that individuals undergoing IORT have a greater likelihood of recurrence in the same breast compared to those undergoing EBRT. Despite this, the survival rates for breast cancer following both types of radiation therapy are similar. The primary drawbacks of IORT include potential fluid buildup in breast tissue and temporary bruising.


In the event that IORT is recommended for you, you will probably go through the following procedures:

  • In the operating room, anesthesia will be administered to you.
  • Your surgeon will perform a lumpectomy while you are unconscious, making a breast incision and extracting the tumor.
  • After the tumor is removed, your healthcare provider will insert the IORT device’s applicator straight into the “tumor bed,” or the opening where the tumor was.
  • The radiation dose will be applied directly to the tumor bed through the applicator. It can take up to thirty minutes for the treatment.
  • The applicator will then be removed.
  • The incision will then be closed by your surgeon.

After an IORT lumpectomy, your healthcare provider will conduct cancer cell detection tests on the surrounding lymph nodes and the tumor margin—the area of tissue surrounding the tumor. If these tests indicate the presence of cancer cells, your provider may recommend EBRT to minimize the risk of recurrence.


The following are benefits provided by IORT.

  • Daily treatments for an average of six weeks are frequently necessary for traditional radiation therapy. One-time radiation therapy with a single dose is provided via IORT.
  • IORT is far less expensive than conventional radiation therapy because it only needs one radiation dosage.
  • Less radiation exposure to healthy tissue compared to EBRT. IORT exposes surrounding healthy tissue and organs to less radiation.