Stereotactic Body Radiation Therapy for Spinal Metastases: Tumor Control Probability Analyses and Recommended Reporting Standards. Int J Radiat Oncol Biol Phys 2021 May 01;110(1):112-123
Date
02/01/2021Pubmed ID
33516580DOI
10.1016/j.ijrobp.2020.11.021Scopus ID
2-s2.0-85100092459 (requires institutional sign-in at Scopus site) 21 CitationsAbstract
PURPOSE: We sought to investigate the tumor control probability (TCP) of spinal metastases treated with stereotactic body radiation therapy (SBRT) in 1 to 5 fractions.
METHODS AND MATERIALS: PubMed-indexed articles from 1995 to 2018 were eligible for data extraction if they contained SBRT dosimetric details correlated with actuarial 2-year local tumor control rates. Logistic dose-response models of collected data were compared in terms of physical dose and 3-fraction equivalent dose.
RESULTS: Data were extracted from 24 articles with 2619 spinal metastases. Physical dose TCP modeling of 2-year local tumor control from the single-fraction data were compared with data from 2 to 5 fractions, resulting in an estimated α/β = 6 Gy, and this was used to pool data. Acknowledging the uncertainty intrinsic to the data extraction and modeling process, the 90% TCP corresponded to 20 Gy in 1 fraction, 28 Gy in 2 fractions, 33 Gy in 3 fractions, and (with extrapolation) 40 Gy in 5 fractions. The estimated TCP for common fractionation schemes was 82% at 18 Gy, 90% for 20 Gy, and 96% for 24 Gy in a single fraction, 82% for 24 Gy in 2 fractions, and 78% for 27 Gy in 3 fractions.
CONCLUSIONS: Spinal SBRT with the most common fractionation schemes yields 2-year estimates of local control of 82% to 96%. Given the heterogeneity in the tumor control estimates extracted from the literature, with variability in reporting of dosimetry data and the definition of and statistical methods of reporting tumor control, care should be taken interpreting the resultant model-based estimates. Depending on the clinical intent, the improved TCP with higher dose regimens should be weighed against the potential risks for greater toxicity. We encourage future reports to provide full dosimetric data correlated with tumor local control to allow future efforts of modeling pooled data.
Author List
Soltys SG, Grimm J, Milano MT, Xue J, Sahgal A, Yorke E, Yamada Y, Ding GX, Li XA, Lovelock DM, Jackson A, Ma L, El Naqa I, Gibbs IC, Marks LB, Benedict SMESH terms used to index this publication - Major topics in bold
Cancer PainDose-Response Relationship, Radiation
Humans
Logistic Models
Models, Biological
Models, Theoretical
Probability
Radiosurgery
Radiotherapy Dosage
Spinal Neoplasms
Treatment Outcome
Tumor Burden