Intraoperative radiation therapy in the management of early stage breast cancer

Adjuvant radiotherapy (RT) following breast conserving surgery (BCS) is associated with an improvement in local control and a reduction in breast cancer mortality. While traditionally delivered with whole breast irradiation (WBI), novel approaches have looked to reduce the duration, target volume, and toxicity of adjuvant RT. One such approach is intraoperative radiation therapy (IORT), which delivers radiation at the time of surgery with 80-90% of patients not requiring additional WBI. The current review presents IORT techniques and outcomes from modern series evaluating IORT as monotherapy or as a tumor bed boost. Based on two randomized trials (TARGIT-A and ELIOT) with recent updates, concern regarding higher rates of local recurrence with IORT exist, whether using electrons or low-energy techniques. In contrast, data is promising regarding IORT used as a boost, with ongoing studies evaluating its role prospectively. With respect to toxicity, the data suggest IORT is associated with comparable to slightly lower rates of toxicity though there may be a higher risk of seroma requiring aspiration and fat necrosis with IORT. Given current data and guidelines, WBI or other partial breast techniques should remain the standard of care in early stage breast cancer patients, while IORT should not be utilized outside of prospective clinical trials at this time.