Breast Cancer Radiation in the Modern Era: Intraoperative Radiation Therapy

Posted on: August 19, 2014

Breast Cancer Radiation in the San Francisco Bay Area

Dr. Rahman

By: Sophia Rahman, MD

With the rise in breast cancer screening by mammography, more and more women are being diagnosed at an early stage, increasing the need for proper clinical management of early-stage breast cancer. If you’re looking for breast cancer radiation in the San Francisco Bay area, you’ll want to finish reading this. Over the last five decades, the paradigm of early-stage breast cancer management has shifted from radical mastectomy to breast conservation therapy. Breast conservation therapy classically refers to surgical excision of the tumor with or without axillary lymph node dissection, followed by whole breast external beam radiation therapy to reduce the risk of local recurrence. In most patients, an additional boost dose of radiation is added to the tumor bed.  Although this tends to be a well-tolerated treatment, it does carry a risk of acute and long-term complications, and it requires a daily commitment from the patient for at least 4-7 weeks. Convenience, access, cost, and logistical issues can sometimes make the traditional course of radiation therapy difficult for many of our patients.
It has been shown in both retrospective and prospective clinical trials that more than 80 percent of breast cancer recurrences occur at or near the lumpectomy site. This realization has sparked the rationale for accelerated partial breast irradiation (APBI), which is an approach that treats the lumpectomy cavity plus a 1-2 cm margin in a short amount of time. Some APBI options include balloon brachytherapy, 3D conformal partial breast irradiation, and the most recent development of intraoperative radiation therapy.
Intraoperative radiation therapy (IORT) is an exciting technique that allows us to deliver a concentrated dose of radiation to the tumor cavity at the time of surgery, with the goal of eradicating any microscopic tumor cells that may have been left behind. The procedure involves the placement of a balloon into the lumpectomy cavity, which is connected to a device that generates low energy 50 kV x-rays. A dose of 20 Gray in a single session is delivered to the surface of the tumor bed that attenuates to 5-7 Gray at a 1cm depth.
In 2010, a landmark breast IORT study, the TARGIT trial, was published in Lancet (Vaidya et al). Overall outcomes were non-inferior to traditional radiation techniques. In addition, radiation toxicity was lower in the IORT group than in the external beam radiation group. If the excellent results continue to hold up long-term, then this approach has the potential to increase the efficiency of patient care with the added benefit of decreasing the overall cost of care.
IORT has several key advantages:
–       High Efficacy: IORT has the radiobiologic advantage of targeting the tumor bed at the time of surgery, not allowing the tumor cells time to repopulate. In contrast, traditional radiation techniques require a recovery period of at least four weeks prior to treatment, which results in some tumor cell repopulation.
–       Better sparing of normal tissues: The IORT technique allows for precise delivery of the radiation dose to the tumor bed, without affecting the skin, surrounding normal tissue, lungs, and heart. Tumor bed motion with respiration is not a concern as the balloon moves with the patient. Because the treatment is so precise, a very high dose can be delivered to the area in a single treatment.
–       Shortest Possible Treatment Time: IORT allows for radiation delivery to take place right at the time of surgery, and takes only 5-10 minutes for radiation delivery. The patient has completed treatment even before recovering from anesthesia, as opposed to the cumbersome traditional treatments that take several weeks to complete.
–       Radiation Boost: Some women may have indications for additional radiation therapy, for example if they have high risk features not known at the time of surgery. In these cases, the IORT treatment can be regarded as a boost and the patient can move on to whole breast radiation therapy, which still shortens the entire course of therapy by at least one week.
At Diablo Valley Oncology, we have partnered with local breast surgeons and offer the breast IORT procedure at Aspen Surgery Center at John Muir Medical Center. IORT is generally reserved for a subset of women with early-stage disease and should be discussed in a formal consultation with one of our experienced radiation oncologists to determine if the patient is a good candidate. As always, we will continue to provide the most comprehensive treatment options and the latest cutting edge technology for our patients.
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