TOPLINE:
For patients with nonspine bone metastases, stereotactic body radiation therapy (SBRT) is a safe and effective treatment, with low rates of local failures and fractures as well as minimal serious toxicity, according to pooled data.
METHODOLOGY:
- Bones are common sites for cancer metastasis; nonspine lesions make up about 30% of bone metastases. SBRT may be a viable treatment option, but the long-term safety and efficacy of SBRT in this setting is limited.
- Researchers conducted a meta-analysis of seven trials including 807 patients with 1048 nonspine bone metastases treated with SBRT, with the median follow-up period ranging from 7.6 months to 26.5 months.
- The most common SBRT sites were pelvis (39.2%), ribs (25.8%), femur (16.7%), and humerus/shoulder region (8.7%).
- The median biologically effective dose of SBRT was 56.7 Gy, corresponding to a dose of 33-34 Gy in five fractions or 28-29 Gy in three fractions.
- Meta-regression was used to examine clinical and treatment factors associated with outcomes of interest, including local failure, pathological fracture, overall survival, progression-free survival (PFS) and toxicity.
TAKEAWAY:
- The 1- and 2-year local failure rates were 7% and 12%, respectively. Clinical factors such as lesion type, oligometastatic condition, biologically effective dose, and planning target volume were not associated with local failure.
- The 1-year fracture rate was 5.3%. The ribs and pelvis were the most common fracture sites. Planning target volume was the only factor associated with fracture risk, which showed a linear relationship between volume and fracture risk, regardless of the treated site.
- At 1 year, overall survival was 82% and PFS was 33.5%. Median overall survival was 20.2 months and PFS was 8.3 months.
- Overall toxicity was low with < 1% experiencing grade 3 toxicity. The most common toxicities were pain flare (7.0%), fatigue (5.4%), and dermatitis (0.7%).
IN PRACTICE:
While this meta-analysis demonstrates the safety and efficacy of SBRT with “infrequent” grade 3 toxicities, the authors emphasized that “careful consideration of target volume is crucial due to its link with a higher fracture risk.”
SOURCE:
The study, with first author Fabio Ynoe Moraes, PhD, MD, Division of Radiation Oncology, Kingston General Hospital, Queen’s University, Ontario, Canada, was published online on January 18, 2024, in the International Journal of Radiation Oncology, Biology, Physics.
LIMITATIONS:
The retrospective design of most studies led to heterogeneity in the patient sample, with different target treatment volumes, SBRT dose/fractionation and treated sites. There was no assessment of pain relief from SBRT mainly due to a high rate of asymptomatic nonspine bone mets treated.
DISCLOSURES:
The study had no specific funding. Moraes reported consulting fees from Elekta and honoraria from AstraZeneca.