Definitive Stereotactic Body Radiotherapy (SBRT) for Extracranial Oligometastases: An International Survey of >1000 Radiation Oncologists

PURPOSE: Stereotactic body radiotherapy (SBRT) is often used to treat patients with oligometastases (OM). Yet, patterns of SBRT practice for OM are unknown. Therefore, we surveyed radiation oncologists internationally, to understand how and when SBRT is used for OM.

METHODS: A 25-question survey was distributed to radiation oncologists. Respondents using SBRT for OM were asked how long they have been treating OM, number of patients treated, organs treated, primary reason for use, doses used, and future intentions. Respondents not using SBRT for OM were asked reasons why SBRT was not used and intentions for future adoption. Data were analyzed anonymously.

RESULTS: We received 1007 surveys from 43 countries. Eighty-three percent began using SBRT after 2005 and greater than one third after 2010. Eighty-four percent cited perceived treatment response/durability as the primary reason for using SBRT in OM patients. Commonly treated organs were lung (90%), liver (75%), and spine (70%). SBRT dose/fractionation schemes varied widely. Most would offer a second course to new OM. Nearly all (99%) planned to continue and 66% planned to increase SBRT for OM. Of those not using SBRT, 59% plan to start soon. The most common reason for not using SBRT was lack of clinical efficacy (48%) or lack of necessary image guidance equipment (34%).

CONCLUSIONS: Radiation oncologists are increasingly using SBRT for OM. The main reason for not using SBRT for OM is a perceived lack of evidence demonstrating clinical advantages. These data strengthen the need for robust prospective clinical trials (ongoing and in development) to demonstrate clinical efficacy given the widespread adoption of SBRT for OM.