External beam radiation therapy (EBRT) for asymptomatic bone metastases in patients with solid tumors reduces the risk of skeletal-related events (SREs).

BACKGROUND: The potential benefit of administering external beam radiation therapy (EBRT) to patients with asymptomatic bone metastases has rarely been addressed in clinical investigations. The aim of this study was to determine if cancer patients who were treated with EBRT for asymptomatic bone metastases experienced later onset of pain and skeletal-related events (SREs) than those who were untreated.

METHODS: A retrospective chart review was conducted for prostate, breast, and lung cancer patients with asymptomatic bone metastases treated at a single cancer center from 2007 to 2017. Patients who received EBRT for asymptomatic bone metastases were compared to those who received medical or supportive therapy only.

RESULTS: When all cancer groups were combined, the median time from the diagnosis of asymptomatic bone metastases to either moderate-to-severe pain or an SRE was 25 months for the untreated patients and 81 months for the patients receiving EBRT (P<0.001). The delay in the first occurrence of pain or an SRE following EBRT was observed for patients with prostate cancer (P=0.025) and lung cancer (P=0.029) but not for patients with breast cancer. In a multivariate analysis, EBRT was again shown to reduce the risk of developing pain or an SRE when all cancer types were combined (P=0.006). OS was not altered by EBRT.

CONCLUSIONS: EBRT administered to a group of prostate, lung, and breast cancer patients with asymptomatic bone metastases was associated with an increase in time to the first occurrence of either pain or an SRE. These data demonstrate that there may be clinical settings in which EBRT should be used to delay or prevent late complications of bone metastases that are asymptomatic at the time of diagnosis.