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Published on: May 8, 2018
Assessing the effect of metastasis-directed therapy in oligometastatic disease using the restricted mean survival
Itamar Averbuch1, Assaf Moore2, Ethan B Ludmir3
1Davidoff Cancer Center, Rabin Medical Center - Beilinson Hospital, Petach Tikva, Israel. av.itamar@gmail.com.
Background:
Metastasis-directed therapy (MDT) with stereotactic body radiotherapy (SBRT) is emerging as an effective therapeutic option for oligometastatic disease (OMD). However, a lack of phase III data, consensus guidelines, and toxicity concerns limit its widespread use. Randomized controlled trials (RCTs) routinely report hazard ratios (HRs) and medians that lack clear clinical and robust interpretation. Restricted-mean survival time (RMST) is the duration of time a patient is expected to survive over the follow-up period, providing a robust and interpretable alternative. We analyzed the efficacy of SBRT using RMST.
Methods:
All registered RCTs of ablative radiotherapy in OMD in ClinicalTrials.gov through 2022 were identified. Data were reconstructed from Kaplan-Meier curves, and the HRs and RMST differences were estimated for surrogate endpoints (SEs) and overall survival (OS).
Results:
Six studies comprising 426 patients met the inclusion criteria. The RMST differences for SEs ranged from 4.6 months in a study by Iyengar et al. to 11.1 months in SABR-COMET. The RMST differences for OS in SABR-COMET, Gomez et al., and SINDAS studies were 12.6, 15 and 7.9 months, respectively.
Conclusion:
RMST demonstrates the efficacy of local treatment in OMD. Representing the expected survival time, this method effectively communicates outcomes to patients and clinicians.
Insights
Restricted-mean survival time (RMST) analysis shows stereotactic body radiotherapy (SBRT) effectively treats oligometastatic disease (OMD). This method offers clearer interpretation of survival benefits for patients and clinicians.
Area of Science:
- Oncology
- Radiation Oncology
- Clinical Trials
Background:
- Metastasis-directed therapy (MDT) using stereotactic body radiotherapy (SBRT) shows promise for oligometastatic disease (OMD).
- Widespread adoption is hindered by limited phase III data, lack of guidelines, and toxicity concerns.
- Traditional metrics like hazard ratios (HRs) offer limited clinical interpretation.
Purpose of the Study:
- To evaluate the efficacy of SBRT in OMD using restricted-mean survival time (RMST).
- To provide a more robust and interpretable measure of survival outcomes compared to HRs.
Main Methods:
- Systematic review of randomized controlled trials (RCTs) of ablative radiotherapy for OMD registered on ClinicalTrials.gov through 2022.
- Reconstruction of data from Kaplan-Meier curves to estimate HRs and RMST differences.
- Analysis focused on surrogate endpoints (SEs) and overall survival (OS).
Main Results:
- Six RCTs with 426 patients met the inclusion criteria.
- RMST differences for SEs ranged from 4.6 to 11.1 months.
- RMST differences for OS were 12.6 months (SABR-COMET), 15 months (Gomez et al.), and 7.9 months (SINDAS).
Conclusions:
- RMST analysis confirms the efficacy of SBRT as a local treatment for OMD.
- RMST provides a clear and interpretable measure of expected survival time.
- This method enhances communication of treatment outcomes to patients and clinicians.
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