Contemporary Statewide Practice Pattern Assessment of the Palliative Treatment of Bone Metastasis

Abstract

Purpose: Palliative radiation therapy for bone metastases is often viewed as a single entity, despite national guidelines providing input principally only for painful uncomplicated bone metastases. Data surrounding the treatment of bone metastases are often gleaned from questionnaires of what providers would theoretically do in practice or from population-based data lacking critical granular information. We investigated the real-world treatment of bone metastases with radiation therapy.

Methods and materials: Twenty diverse institutions across the state of Michigan had data extracted for their 10 most recent cases of radiation therapy delivered for the treatment of bone metastases at their institution between January and February 2017. Uni- and multivariable binary logistic regression was used to assess the use of single fraction (8 Gy × 1) radiation therapy.

Results: A total of 196 cases were eligible for inclusion. Twenty-eight different fractionation schedules were identified. The most common schedule was 3 Gy × 10 fractions (n = 100; 51.0%), 4 Gy × 5 fractions (n = 32; 16.3%), and 8 Gy × 1 (n = 15; 7.7%). The significant predictors for the use of single fraction radiation therapy were the presence of oligometastatic disease (P = .008), previous overlapping radiation therapy (P = .050), and academic practice type (P = .039). Twenty-nine cases (14.8%) received >10 fractions (median 15, range 11-20). Intensity modulated radiation therapy was used in 14 cases (7.1%), stereotactic body radiation therapy in 11 (5.6%), and image guidance with cone beam computed tomography in 11 (5.6%). Of the cases of simple painful bone metastases (no previous surgery, spinal cord compression, fracture, soft tissue extension, or overlapping previous radiation therapy; n = 70), only 12.9% were treated with 8 Gy × 1.

Conclusions: Bone metastases represent a heterogeneous disease, and radiation therapy for bone metastases is similarly diverse. Future work is needed to understand the barriers to single fraction use, and clinical trials are necessary to establish appropriate guidelines for the breadth of this complex disease.

Fig. 1.

Heterogeneity in dose fraction schedules. (A) Scatter plot of dose per fraction and number of fractions for all 196 cases. Size of the sphere correlates to frequency. (B) Stacked bar chart of the biologically equivalent dose using an α/β of 10 according to treatment planning technique used. Abbreviations: 2D = 2-dimensional; 3D = 3-dimensional; IMRT = intensity modulated radiation therapy; MLC = multileaf collimator; VMAT = volumetric modulated arc therapy.

Fig. 2.

Heterogeneity in use of single fraction radiation therapy (8 Gy × 1) stratified by institution. (A) Cumulative probability of single fraction radiation therapy use stratified by institution among all cases (n = 196). (B) Cumulative probability of single fraction radiation therapy use stratified by institution for only painful bone metastases (pain score >4 of 10) and no previous overlapping radiation therapy, soft tissue extension, spinal cord compression, pathologic fracture, or surgery (n = 70). Red X denotes no cases present at that center.

Fig. 3.

Distribution of intensity modulated radiation therapy (IMRT) and single fraction (SF) use stratified by institution.