Catheryn Yashar, M.D.

Catheryn Yashar, M.D. presented the results of her early experience with the SAVI applicator at the annual meeting of the American Brachytherapy Society, held May 31-June 2, 2009, in Toronto. Here she discusses the results of her study, how SAVI plays a role in the advancement of APBI and the future of breast brachytherapy.

How was your study on SAVI received?

It was very well-received. This study was significant because with a full year of data, it represents the longest follow-up for SAVI to date. The results confirmed previous findings – it enabled us to spare the skin, there were no complications and it allowed us to treat a significant portion of the patients who would have been ineligible for treatment with standard balloon brachytherapy. In fact, 38% of the patients in this study would not have been candidates for partial breast radiation prior to the availability of SAVI.

I think what interests physicians the most is the flexibility that SAVI offers. You can spare normal tissue without the concern that the device is too close to the skin or chest wall. I had many approach me after the presentation for more information on SAVI’s clinical and dosimetric advantages, and the hands-on session for SAVI that I led later in the week was very well attended.

What were some of the hot topics discussed at this year’s meeting of the American Brachytherapy Society

There was a great deal of excitement about partial breast radiation therapy, particularly surrounding the newer devices like SAVI. But there’s still a level of caution, because the follow-up on these devices is relatively brief. Most physicians are comfortable offering APBI to patients in the low-risk category, such as women over 60 with small tumors. But we have less data on the efficacy of APBI for higher risk groups, like younger women or patients with high grade DCIS.

In fact, there was a lot of discussion regarding the use of APBI to treat DCIS, especially because of the recent release of the American Society for Radiation Oncology (ASTRO) patient selection guidelines. The ASTRO guidelines placed DCIS in the “treat with caution” category, while other organizations, like the American Society of Breast Surgeons, say DCIS is not a contraindication for APBI. There is concern that the ASTRO guidelines could be misused – that insurance companies won’t provide reimbursement for patients with DCIS by saying it’s experimental. Instead of using the guidelines to counsel patients, they become guidelines for which people should not be offered APBI because of a lack of reimbursement. That’s an area of concern that was widely discussed at the meeting.

The other hot topic was the Canadian fractionation method, in which higher doses of external beam whole breast irradiation are delivered over a period of 16 days. Researchers recently presented10-year data demonstrating that tumor control, effects under treatment and long-term effects are equivalent to whole breast radiation, making it a reasonable alternative to the standard six-week treatment. Now that we have 10-year follow-up, American physicians are starting to take notice.

What were the opinions on partial breast versus whole breast radiation, the current standard-of-care?

Most of the debates at the meeting focused on the topic of partial breast versus whole breast. Many participants at the meeting were fairly conservative. They believe that for the low-risk patient population, partial breast radiation is an acceptable alternative to whole breast. But for the intermediate and high-risk groups, some were reluctant to offer APBI until we have more experience and more data. I don’t think the discussions changed many opinions – most people felt the same way before and after the debates.

What were the opinions on the various breast brachytherapy devices?

Many discussions focused on comparing the newer devices to MammoSite, the current gold-standard for breast brachytherapy. By now, most of the medical community recognizes the limitations of the balloon. If fact, it was the subject of many talks and posters presented at the meeting – there’s plenty of data that shows you can’t get as close to the skin or chest wall. It’s become quite clear that MammoSite simply cannot compete with the newer devices like SAVI in terms of treating more patients and sparing normal tissues.

There is still a patient population that can benefit from MammoSite. It is still useful in patients with large breasts and with large cavities in the middle of the breast. But it just cannot compete with devices like SAVI for small-breasted women, small cavities, or women with tumor beds adjacent to critical structures.

How does the medical community feel about the various methods of APBI?

There’s a great deal of debate about 3D conformal radiation therapy versus brachytherapy. In particular, there has been a lot of concern expressed about 3D conformal. We know that 3D conformal treats more normal tissue than brachytherapy, but there are concerns that it may result in more toxicity than originally thought. A majority of the patients in the NSABP-39 trial are receiving 3D conformal, so it’s possible we’ll have that answer soon. But some early reports suggest untoward long-term effects like fibrosis and hyperpigmentation of the skin, rib fractures and even one report of pericarditis. Obviously, this leads to the argument that brachytherapy – which can provide effective treatment while sparing normal tissue and reducing toxicity – should be the preferred method of treatment.

What has been the biggest development in breast brachytherapy in the past several years?

Certainly, MammoSite was the earliest breakthrough. Although interstitial brachytherapy had been available for some time, the significant learning curve limited its use. MammoSite’s ease-of-use revolutionized APBI and breast brachytherapy, making it far more popular. Fortunately, once the balloon’s limitations were recognized, devices like SAVI were developed to offer APBI to an even greater number of women with less toxicity. This has been another significant step forward since Dr. Kuske first introduced interstitial brachytherapy for APBI.

Where do you see breast brachytherapy in the next 5-10 years?

I think brachytherapy will be favored over 3D conformal as the desired method for administering APBI. I also have no doubt there will be a population of women for whom breast brachytherapy can be the standard of care.

The question that remains is how many women that population will encompass. It will likely include patients in what we now consider the low-risk group, as well as some in the intermediate group. But how far into the intermediate group, and whether it includes women in the high-risk group as well, remains to be seen. It’s too early to tell. We simply don’t have enough data on those particular populations – but it will come.

About Dr. Yashar
Dr. Yashar is Associate Professor and Chief of Breast and Gynecological Services in the University of California, San Diego’s Department of Radiation Oncology. The Moores Cancer Center at UC San Diego was the second medical facility in the nation to offer SAVI for breast brachytherapy.