Targeted Radiation Therapy Gaining Momentum

October 2011, Vol 2, No 6

San Francisco, CA—Accelerated partial breast irradiation using brachytherapy (APBIb) for breast cancer has been rapidly adopted in the United States, although its use varies by region, race, and ethnicity. Jona A. Hattangadi, MD, Harvard Radiation Oncology Program, Boston, reported the findings at the 2011 ASCO Breast Cancer Symposium, which was sponsored by 6 breast, oncology, and surgical societies.

APBIb, a new alternative to whole breast irradiation (WBI), delivers radiation only to tissue within a few centimeters of the excision cavity (the area at highest risk for cancer recurrence). It has the advantage of decreased treatment time and lower radiation dose to uninvolved tissues.

The concern is, however, that occult foci of cancer may exist elsewhere in the breast and are thus not well treated. The lack of long-term data and the possible expense of the approach are also of concern, Dr Hattangadi said.

Dr Hattangadi and colleagues evaluated radiation therapy patterns in 138,815 patients with breast cancer using the Surveillance, Epidemiology and End Results (SEER) database.

Patients received APBIb or WBI after lumpectomy from 2000 to 2007 and were classified as “suitable,” “cautionary,” or “unsuitable” for APBIb based on the 2009 guidelines of the American Society for Radiation Oncology. Unsuitable patients, according to these guidelines, are those with tumors >3 cm, extensive lymphovascular invasion, and no lymph node surgery.

The current analysis showed a steadily rising trend for APBIb use; by 2007, 7% of the patients in the SEER database were treated with this approach overall. The use of APBIb rose steeply after 2002, when balloon brachytherapy received US Food and Drug Administration approval, and again in 2004, when Medicare began reimbursing for this treatment. The rise in use was seen across all 3 patient categories, with the steepest increase among suitable patients.

Disparities in APBIb Use

Significant differences in the use of APBIb exist, the study shows. Nonwhite patients are 20% to 50% less likely to receive APBIb than white patients, as are persons living outside of or adjacent to metropolitan areas versus those living in metropolitan areas. Patients aged ≥60 years are more likely to receive APBIb than younger patients.

Geographical variation is common, with the highest rates of APBIb use in Atlanta, rural Georgia, Louisiana, Utah, and Kentucky. Patients in Atlanta were almost 13 times more likely to receive APBIb than patients in Hawaii and were 22 times more likely to receive APBIb if they fell into the unsuitable category.

These same high-use regions had increased rates of APBIb use among unsuitable patients, Dr Hattangadi said, adding, “The odds ratio for use increased as the appropriateness of use decreased.”

From 2006 to 2007, the use of APBIb increased 15-fold compared with the period between 2000 and 2002. Patients with larger tumor size and invasiveness, worse histologic grade, and positive lymph nodes were up to 50% less likely to receive APBIb.

Oncologists’ Perspectives

Robert Kuske, MD, Arizona Breast Cancer Specialists, Phoenix, AZ, who pioneered the brachytherapy approach years ago, commented on these findings to Value-Based Cancer Care, pointing out that the use of APBIb in unsuitable patients should not be considered out of line.

“The APBIb movement started in Louisiana [where he practiced at the time] and is now being done all over the world. When I started it, and before guidelines were established, I wanted to be inclusive, not exclusive, in patient selection for my trials, to determine if APBIb was as good as, better than, or worse than WBI in aggressive cancers. Therefore, I included all different subtypes of the disease. I argued that dose-dense radiation, which you get with APBIb, might actually be more effective for the worst cancers. Some of my colleagues were skeptical and reserved it for the best of the best of cancers,” Dr Kuske said.

“Since I am the only investigator who included the unfavorable subset, and the guidelines were established based on the amount of evidence in patient groups, the unsuitable category is not based on negative data but on a paucity of data,” Dr Kuske said.

Rakesh Patel, MD, Western Radiation Oncology, El Camino, CA, also commented on ths study. He agreed that the terms “suitable” and “unsuitable” are “difficult to interpret by patients and physicians,” adding that “it only takes 1 feature to ratchet patients” to a higher-risk category.

“There are no data to suggest that cautionary or unsuitable patients do worse,” Dr Patel said. “We have to be careful when we look at the guidelines and interpret them as right or wrong. We have to look at the complexity of patients.”

After a 6-year period of follow-up in the MammoSite registry trial, no differences in outcomes have emerged between the unsuitable and the suitable/ cautionary guideline groups, said Dr Patel. “We should treat the patient, not the guidelines.”

In doing so, it is possible to observe cost-savings. “This is not more expensive, although it used to be. Things have changed. In fact, it’s less expensive,” Dr Patel added, describing data from his practice area (Table).

“APBIb also has value when taking into account less time spent away from work and family and the other parameters that go into complex decisionmaking,” he added.

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