Radiation therapy is a standard part of the treatment of breast cancer when lumpectomy or breast-conserving surgery (BCS) is performed. The purpose of radiation therapy is to reduce the risk of cancer recurrence within the breast.

How Is IORT Administered?

Traditional whole-breast radiation therapy is typically administered as a 3- to 6-week course of daily radiation treatment after recovery from surgery; however, intraoperative radiotherapy (IORT) is administered in a single dose during breast-conserving surgery. IORT is completed in as little as 2 minutes depending on the IORT system used to deliver the therapy.

While traditional radiation therapy is administered to the entire breast, IORT is a form of partial breast radiation that is focused only on the part of the breast from which the tumor was removed. This type of therapy spares the rest of the breast the side effects of radiotherapy. (During IORT, internal radiation shielding may be used to protect the heart and nearby lung.)

Who Is Appropriate for This Treatment?

Only patients with smaller tumors are eligible for IORT. Some facilities use oversight committees to be sure this treatment is appropriate for an individual patient. There is variability to the size and age of the women offered IORT (some use less than 2.5 or 2.0 cm and age has gone as young as 40 in some cases) and negative lymph nodes. IORT is most commonly administered as the sole source of radiation therapy. However, IORT may also be combined with traditional whole-breast radiation therapy for women at greater risk of local recurrence. Women found to have larger or more extensive breast cancers may additionally be required to undergo whole-breast radiotherapy to minimize the risk of local recurrence.

What Are the Advantages and Disadvantages of IORT?

The main advantages of IORT are the convenience of receiving breast radiotherapy at the time of breast surgery and the ability of the surgeon to actively shield nearby tissues from the side effects of radiation. The main disadvantage of IORT is that the treatment is administered before the status of the surgical margins and lymph nodes are known, which may necessitate additional radiotherapy and/or surgery in a minority of patients. Therefore, proper patient selection is key to the success of this treatment. Another disadvantage is that there are no long-term studies comparing the effectiveness of IORT to traditional whole-breast radiotherapy. However, recent studies with 5-year follow-up results show equal effectiveness between the 2 treatments and, when IORT is administered to eligible patients, fewer side effects among IORT recipients.