Moffitt Onco Update

Improving Outcomes with Personalized Radiation Therapy for Breast Cancer Patients

October 18, 2014

intrabeam Onco Update.jpg Intraoperative radiation therapy (IORT) delivers a concentrated dose of radiation therapy to the tumor while preserving healthy tissue. The Intrabeam® miniature mobile X-ray source emits low energy radiation in isotropic distribution.

Susan J. Hoover, MD, FACS

For those of us who have treated breast cancer patients for any extended period of time, we likely have tales of watching the treatment of this disease evolve to levels many of us could only have imagined. Noteworthy in the last several years is the popularization of breast conservation surgery and the advancement of radiation options that go hand-in-hand with it.

With 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 that live far away from radiation centers.

A 2005 study in the Journal of Clinical Oncology found this to be true with a 40% mastectomy rate in women that lived less than 10 miles from a radiation center and 55% in those that lived greater than 50 miles away from a center. 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 is with undergoing the radiation.

A second study in the Journal of the National Cancer Institute (2000) showed that those living less than 25 miles from a radiation facility had surprisingly only an 84% compliance rate, which declines even further with increasing distance such that 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.

A whole host of radiation therapy regimens are now available to help provide women interested in breast conservation the possibility of annotated 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, Moffitt Cancer Center has been offering appropriately selected candidates shorter courses of radiation after lumpectomy including hypofractionated whole breast radiation therapy over 3-4 weeks, accelerated partial breast irradiation (APBI) over 1 week and intraoperative radiation therapy (IORT) given in 1 treatment while the patient is still under anesthesia at time of lumpectomy.

In 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. This has hence created 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, like 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 EBRT including:

  • Skin irritation/pigmentation changes
  • Breast tissue fibrosis
  • Fatigue
  • Heart and lung exposure
  • Effects to the normal, healthy breast tissue

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 then conformed around the applicator/X-ray source, and then 20 Gy in one fraction is delivered to the lumpectomy cavity for approximately 20-40 minutes, depending on the size of the applicator.

The INTRABEAM® was used internationally as part of the TARGeted Intraoperative radioTherapy (TARGIT-A) Trial comparing IORT to traditional whole breast external beam radiation therapy (EBRT). The TARGIT-A trial, randomized 3,451 women equally to IORT and external beam whole breast radiation therapy with the 5-year results for local control and overall survival published in Lancet February 2014. The data showed that when IORT was given with lumpectomy, the 5-year local recurrence rate was similar to EBRT.  As well, breast cancer mortality between the 2 groups was also similar.

IORT has allowed some women to undergo lumpectomy who otherwise would have chosen a mastectomy due to work situations, transportation issues or personal/family circumstances that made travel to a radiation facility 5 days a week for 6 weeks difficult to execute. IORT allows for them to choose a lumpectomy, if that is their surgical treatment of choice, without the worry of completing the necessary radiation that must follow a lumpectomy.

Although an enticing option, it is key to emphasize that IORT and APBI are not for every breast cancer patient. The American Society for Radiation Oncology (ASTRO) published a consensus statement for accelerated partial breast irradiation providing guidance for patient selection and includes the following factors to be considered.

 Optimal candidates

  • 60 years old
  • Tumor size <2cm
  • Surgical margins >2mm
  • Estrogen receptor positive tumors
  • Invasive Ductal Carcinoma histology
  • Lymph node negative

 “Cautionary” candidates

  • 50-59 years old
  • Tumor size 2.1-3.0 cm
  • Surgical margins <2mm
  • Estrogen receptor negative tumors
  • Invasive Lobular Carcinoma histology
  • Pure DCIS <3cm

Since January 2011, Moffitt has treated over 100 women with IORT.  This technique has provided our patients with early stage breast cancer an option that is state-of-the-art, allowing many of them latitude in their surgical decision making with equivalent outcomes to more traditional radiation modalities. It is vital to remember that application of such pioneering techniques as IORT requires a team approach of surgeons and radiation oncologists vigilantly selecting appropriate candidates to ensure translation to optimal outcomes and patient satisfaction.

About Dr. Susan Hoover

Dr. Hoover is a board certified surgical oncologist specializing in breast cancer at Moffitt Cancer Center. She returned to Moffitt after several years of practice at MD Anderson Cancer Center in Houston, Texas. In addition to performing breast surgeries, such as mastectomies and lumpectomies, she has special expertise in minimally-invasive surgery techniques, incorporating sentinel lymph node biopsy, breast ultrasound, breast needle biopsy and accelerated partial breast irradiation into her patient care. Dr. Hoover has held national committee appointments in the Society for Surgical Oncology, the American Society of Breast Surgeons and the Association of Women Surgeons. She has been chosen by her peers for listing in Best Doctors in America since 2009. Dr. Hoover is accepting new patient referrals at Moffitt.

 

Adapted from Florida MD, October 2014