Susan J. Hoover, MD, FACS
Center For Women’s Oncology
Moffitt Cancer Center
Those of us who have treated patients with breast cancer for any extended period of time can likely share anecdotes about watching the treatment of this disease evolve to levels many of us could only have imagined when we began practicing. One such noteworthy development in the last several years has been the popularization of breast conservation surgery and the advancement of radiation options that go hand in hand with it.
Yet amid this trend toward more minimally invasive techniques in the treatment of breast cancer, it is disappointing to see that some studies demonstrate that mastectomy rates are higher among patients who live far away from radiation centers.
Schroen et al1
found a 40% mastectomy rate among women who lived less than 10 miles from a radiation center, but a 55% rate among patients who lived greater than 50 miles away from a center.1
Additionally, even among women who have elected to undergo a lumpectomy and the required radiation therapy, it has also been shown that the greater the distance the patient lives from a radiation center, the lower the patient compliance rate is among those undergoing the radiation.
In another study, Athas et al2
found that patients living less than 25 miles from a radiation facility surprisingly have only an 84% compliance rate with their treatment. The compliance level declined even further with increasing distance; only 42% of lumpectomy patients living >100 miles from a radiation facility actually completed the recommended course, thus leaving themselves at increased risk of breast cancer recurrence.
Strategies Aim to Shorten Regimens
A host of radiation therapy regimens are now available to help provide women interested in breast conservation the possibility of abbreviated treatments, thus giving some women the option to save their breasts in lieu of mastectomy.
These additional options for shorter courses of radiation are helping ensure radiation compliance and increasing feasibility of lumpectomy for some women. In addition to the gold standard of conventional whole-breast radiation, given over 6 weeks, the Moffitt Cancer Center has been offering appropriately selected candidates shorter courses of radiation after lumpectomy including hypofractionated whole-breast radiation therapy over 3 to 4 weeks, accelerated partial breast irradiation (APBI) over 1 week, and intraoperative radiation therapy (IORT) given in one treatment while the patient is still under anesthesia at time of lumpectomy.
With respect to the employment of APBI and IORT, it is recognized through multiple clinical trials that approximately 90% of the time, local recurrences after breast conservation therapy occur within the index quadrant of the breast, near the original tumor bed.
Hence, there is a platform for these more localized radiation treatments designed to focus the radiotherapy to the lumpectomy cavity, which is the area most likely to fail and form a recurrence. It has also been observed in studies that partial breast radiation therapies such as IORT lower the overall toxicity and burden of radiation by allowing the use of a lower dose of radiation administered in fewer fractions over a shorter period of time while sparing the rest of the breast and the surrounding organs the effects of radiation therapy.
Specifically, these therapies may also eradicate or reduce many of the possible side effects commonly seen with external-beam radiation therapy (EBRT), including:
Skin irritation/pigmentation changes
Breast tissue fibrosis
Heart and lung exposure
Effects to the normal, healthy breast tissue
IORT Device Used at Moffitt
Moffitt has found success with the INTRABEAM® Radiotherapy device that is employed to deliver IORT. The system comes with several applicators of various sizes that are mounted on the x-ray source. The breast tissue is conformed around the applicator/x-ray source, and then 20 Gy in one fraction is delivered to the lumpectomy cavity for approximately 20 to 40 minutes, depending upon the size of the applicator.