Radiation therapy for asymptomatic bone metastases may improve cancer survival

In a small randomized trial reported here, prophylactic radiation therapy (RT) for asymptomatic bone metastases significantly reduced the incidence of skeletal-related events (SREs) in cancer patients.

Patients who received RT had an SRE rate of 1.6%, compared to an SRE rate of 29% for patients randomized to standard care. SRE pain and hospitalization were also significantly lower in the RT group.

Perhaps more importantly, prophylactic RT was associated with significantly improved overall survival (OS). American Society for Radiation Oncology (ASTRO) Annual Meeting.

“It was somewhat unexpected that patients actually seem to be living longer,” she told an ASTRO press conference. There were previous randomized trials that were examined. [showing that] By keeping patients healthy, more active and potentially avoiding hospital visits, they live longer. More recently, several studies of active symptom monitoring using patient-reported outcomes have shown similar results, but the exact mechanism … needs to be evaluated in future studies.”

“Future studies are needed to confirm overall survival benefits in order to truly optimize patients receiving treatment,” added Dr. Gillespie. “Only 30% of patients had events. For the most vulnerable patients, how do you see them in radiation oncology clinics and ensure that they receive timely treatment?”

Palliative radiation therapy is standard practice for symptomatic bone metastases. However, the benefits of prophylactic RT for asymptomatic lesions in critical skeletal sites remained unclear. Bone metastases can cause considerable pain and lead to hospitalization. A retrospective review confirmed the presence of bone lesions on previous images.

“From a retrospective study, at least 60% of hospitalized patients treated for bone pain [prior] Therefore, the question arises whether irradiating these lesions before they become painful can actually prevent complications such as umbilical cord compression, fractures, and hospitalization, and improve the quality of life of patients.” says Gillespie.

To address this question, researchers enrolled 78 patients with a total of 122 high-risk (due to size, depth, or anatomical location) asymptomatic bone metastases. Primary tumor type was lung in 27% of her patients, breast in 24%, and prostate in 22%.

Patients received either planned standard of care (SOC) (systemic therapy or observation) or SOC and RT for symptomatic bone metastases. The primary endpoint was the 1-year rate of SRE, defined as cancer-related fracture or spinal cord compression, surgery, surgery for bone instability, or RT for pain. OS was the secondary endpoint.

The 27.4% absolute difference in SRE represents a nearly 95% reduction in risk for all SREs (P.<0.0001). SRE-related hospitalization occurred in his 11% of patients randomized to SOC, whereas none of those receiving prophylactic RT. Patients randomized to RT also had a better pain-related quality of life at 1 year.

“If you look at pain-related quality of life over time, you can actually see that radiation is preventing pain in the future. It’s a bit of a paradigm shift,” Gillespie said. “Relaxed settings use only radiation. [when] Patients feel pain, but they may be reluctant to use radiation if they do not have pain.

Data showed that patients who received SOC alone had a median OS of 1 year, compared with a median OS of 1.7 years for patients randomized to prophylactic RT (seeP.= 0.02). Differences in survival persisted after multivariate analysis adjusted for differences in patient characteristics.

Responding to questions about the applicability of the results to clinical practice, Gillespie said the trial’s patients were identified at a radiation oncology clinic because the planned treatment for the primary tumor included radiation therapy. As to whether the results apply to asymptomatic patients seen in medical oncology clinics, “that question is not yet answered,” she said.

Without minimizing the clinical benefits of the study, press briefing moderator Iris Gibbs, MD, Stanford Medicine, California, said the findings reflect the broader role of radiation oncology in the health care delivery system. In addition to preventing hospitalizations and reducing morbidity, he said: Prophylactic radiation therapy may reduce the cost of treatment for cancer patients.