Use of stereotactic radiosurgery (SRS) to treat brain metastases in a variety of cancer types has increased significantly ? but unevenly ? during the past decade, according to a new study published in the Journal of the National Comprehensive Cancer Network.

SRS made mainstream news in 2015 when former President Jimmy Carter was successfully treated with the relatively new radiotherapy approach, which is more targeted and less toxic than traditional whole-brain radiotherapy. He was treated at Emory University in Atlanta, Georgia.

The new study indicates that patients with sociodemographic profiles similar to Carter's (ie, being affluent, white, having private insurance, and undergoing treatment at a major center) were much more likely to receive treatment with the sophisticated technology than other patients. Furthermore, treatment with SRS was associated with significantly longer survival.

The researchers, led by Benjamin H. Kann, Yale University School of Medicine in New Haven, Connecticut, used the National Cancer Data Base (NCDB) to identify 75,953 adults with metastatic non–small cell lung cancer, breast cancer, colorectal cancer, or melanoma who received up-front brain radiotherapy between 2004 and 2014.

Patients were divided into SRS and non-SRS cohorts for the purposes of identifying patient- and facility-level SRS predictors. Of all patients, 12,250 (16.1%) received SRS, and 63,703 (83.9%) received non-SRS. The proportion of patients who received SRS increased annually (9.8% to 25.6%; < .001), and the proportion of facilities using SRS increased annually (31.2% to 50.4%; < .001).

SRS use increased "disproportionately" for patients with income levels of $63,000 and above, as well as for those who were treated at academic facilities, for those who lived in areas with higher percentages of high school graduates, and for those with private insurance, the researchers reported from their multivariable analysis.

On the other hand, being of nonwhite race, having nonprivate insurance, and residing in lower-income or less-educated regions predicted lower SRS use ( P< .05 for each).

These findings are potentially meaningful because treatment with SRS was associated with improved survival. From 2004 to 2013, 1-year actuarial survival improved from 24.1% to 49.6% for SRS patients but only from 21.0% to 26.3% for non-SRS patients (< .001).

"This NCDB analysis demonstrates steadily increasing ? although modest overall ? brain SRS use for patients with metastatic disease in the United States and identifies several progressively widening sociodemographic disparities in the adoption of SRS," study authors wrote.

"The up-front costs, infrastructure, and multidisciplinary expertise needed for SRS delivery compared with traditional whole-brain radiation may be contributing to racial and socioeconomic barriers to access," lead author Dr Kann said.

"Investment in a dedicated radiosurgery system, whether using gamma-knife radiosurgery or linear accelerator–based modifications, can cost several millions of dollars up front. Additionally, physician, physicist, and therapist training is required, which involves time commitment and often off-site course attendance."