Women older than 70 years who have certain early stage breast cancers overwhelmingly receive radiation therapy despite published evidence that the treatment has limited benefit, researchers reported.

The study, published in Cancer (2014; doi:10.1002/cncr.28937),  suggests that doctors and patients may find it difficult to withhold treatment previously considered standard of care, even in the setting of high quality data demonstrating that the advantages are small.

“The onus is on physicians to critically analyze data to shape our treatment recommendations for patients, weighing the potential toxicities of treatment against clinical benefit,” said senior author Rachel Blitzblau, MD, PhD, the Butler Harris Assistant Professor of Radiation Oncology at Duke University Medical Center in Durham, North Carolina.

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Blitzblau and colleagues launched their inquiry to determine whether clinical practice changed as a result of a large randomized, prospective study first published in 2004 that compared treatment options for women ages 70 years and older with early stage hormone-receptor positive breast cancers. The CALGB 9343 study reported limited benefit for adding radiation therapy plus tamoxifen after lumpectomy in older women.

Specifically, 5-year data from the 2004 study showed a small but statistically significant reduction in the rate of cancer recurrence; a similar finding was reported again in 2012 with a decade of data. However, the addition of radiation to tamoxifen after surgery did not improve overall survival among the study participants at either of the reporting periods.

“The discussion at the time of the first CALGB report in 2004 was that we should consider omitting radiation for these women, because the small observed benefits might not be worth the side effects and costs,” Blitzblau said, adding that side effects include fatigue, discomfort, and changes in the radiated breast tissue, among others.

But little has changed following publication of the study, with approximately two-thirds of women still undergoing radiation therapy. Blitzblau and colleagues analyzed cancer treatment patterns from the Surveillance, Epidemiology, and End Results (SEER) registry. They found that before the CALGB study results were published in 2004, 68.6% of older women who would have been eligible for enrollment in the CALGB trial received radiation therapy. In the 5 years after the study was first reported, the rate dropped, but only slightly, to 61.7%.

“The publication of the trial had only a very small impact on practice patterns,” Blitzblau said. “Our findings demonstrate the potential difficulty of incorporating clinical trial data that involves omitting a treatment that has been considered the standard of care.”

She said physicians might have delayed making practice changes until longer-term data was available; the research team’s analysis did not include results after the 10-year data from CALGB was published in 2012. In addition, she said, there is likely lingering concern among both doctors and patients that reducing treatments may worsen outcomes for older women who have excellent overall health and therefore longer life expectancies.

But Blitzblau said the findings of the current study highlight an important and increasingly difficult challenge for physicians, which is striking the right balance between offering effective treatments while also acknowledging the need for more financially efficient medical care.