Media on the SAVI^® Applicator

Overview

Accelerated partial breast irradiation (APBI) is a shortened course of high-dose radiation therapy for early-stage breast cancer patients. APBI is delivered as part of breast conservation therapy (BCT), which consists of lumpectomy surgery followed by radiation.

The traditional approach for radiation therapy as part of BCT has been whole breast irradiation (WBI). A full course of WBI requires daily treatments for 5-7 weeks and exposes the entire breast and surrounding critical structures to radiation. APBI, which was developed to address several issues with WBI, delivers radiation only to the lumpectomy cavity and immediately surrounding tissue.

As a result, APBI offers two significant advantages over WBI: it reduces treatment time from several weeks to just 5 days and spares healthy tissue from radiation. Initial research indicates APBI can be as effective as WBI in terms of survival and controlling local recurrences. Since APBI's introduction in the late 1990s, more than 75,000 women in the U.S. have received this 5-day treatment as an alternative to WBI.

History of APBI

In 2002, the New England Journal of Medicine published the 20 year follow-up results of two randomized clinical trials confirming that women with relatively small breast cancers who received BCT were as likely to be alive and disease-free 20 years later as women treated with mastectomy. BCT is now the standard of care for women diagnosed with early stage breast cancers - representing an estimated 142,000 cases annually in the U.S.

The same randomized trials also provided clear information as to the pattern of local recurrences. After a careful review of the published data, it was determined that a majority of recurrences in the breast of patients who did not receive radiation therapy occurred at or in the area of the tumor bed. In addition, the incidence of developing a new cancer in remote areas of the breast (unrelated to the original lesion) was similar whether or not WBI was administered.

These studies formed the scientific basis for reducing the total volume of breast tissue treated with radiation, because although it is effective, WBI has several disadvantages. The extended treatment schedule can significantly disrupt a woman's life, whether it is interference with family, the cost of missed work, or the difficulty of traveling to a medical facility every day for several weeks.

In fact, research has shown that the potential inconvenience and financial burden of whole breast irradiation is among the reasons that only 10-40 percent of women who are eligible for BCT elect to receive it. In addition, among patients who have early-stage breast cancer and who opted for BCT, 20 percent decline to receive radiation - which triples their risk for cancer recurrence.

APBI was developed to address the limitations of WBI. With APBI, a full course of treatment is delivered twice a day for 5 days. In addition, internal APBI (also known as "breast brachytherapy") delivers less radiation to healthy tissue and organs than external radiation treatment.

Though the efficacy of APBI compared to whole breast irradiation has not been established, early results are promising. Five-year results in most studies show that APBI prevents cancer recurrence at the tumor site about as effectively as conventional WBI. Most of the data in these studies involved an internal form of APBI called interstitial brachytherapy. The definitive study comparing the two forms of treatment is currently underway by the National Surgical Breast and Bowel Project (NSABP), and results are expected by 2013.

APBI Approaches and Issues

The most widely available external form of APBI is three-dimensional conformal external beam radiation therapy (RT), which delivers high-energy X-rays to the tumor site from a source outside the patient's body. In most case that source is a linear accelerator. With careful treatment planning, damage to surrounding normal tissue can be avoided or minimized with this technique. Other external methods include intensity-modulated radiation therapy (IMRT) and intraoperative approaches.

The earliest form of internal APBI, or breast brachytherapy, is called interstitial brachytherapy. Interstitial brachytherapy uses multiple catheters in the breast, with multiple entry and exit points, which provides physicians with flexibility on where the radiation dose is delivered. From a dose conformation standpoint, interstitial has been considered the best available approach to post-surgical radiation therapy. However, it is a technically challenging procedure and requires a high-level of clinical expertise, which has limited its availability.

Intracavitary ("balloon") brachytherapy uses a single catheter attached to a balloon that is inserted into the lumpectomy cavity through a single entry point, making it a technically easier procedure than interstitial brachytherapy. However, the use of only one catheter prevents physicians from having the ability to customize treatment based on the patient's anatomy. Because the radiation dose cannot be shaped, there may be greater risk to healthy tissue, and restrictions, such as the lumpectomy cavity being located too close to the skin or chest wall, limit the number of women who can benefit from this approach.

The SAVI ® Applicator

SAVI offers a hybrid approach to APBI, by combining the single-entry ease of balloon brachytherapy with the multi-catheter precision of interstitial brachytherapy. It is the only single-entry breast brachytherapy device that allows physicians to sculpt the radiation based on patient-specific anatomy. Its multi-catheter, open-architecture design enables physicians to target the radiation dose and reduce exposure of healthy tissue such as the heart, lung, skin and ribs.

SAVI is positioned to grow the market by substantially increasing the number of women who are eligible for APBI. Unlike other brachytherapy techniques, SAVI is not limited by the size, shape or location of the lumpectomy cavity, allowing physicians to offer the benefits of this accelerated treatment to the widest array of women.

Clinical studies on SAVI have been authored by internationally known radiation oncology experts such as Robert Kuske, M.D., and by researchers from institutions such as MD Anderson Cancer Center and UC San Diego Moores Cancer Center. These studies show multi-catheter radiation treatment with SAVI makes the benefits of APBI available to twice as many women, as well as results in better outcomes, including less skin toxicity, reduced risk of infection and improved cosmesis.