Efﬁcacy and toxicity of primary re-irradiation for malignant spinal cord compression based on radiobiological modelling: a phase II clinical trial

British Journal of Cancer, 2023 · DOI: https://doi.org/10.1038/s41416-022-02078-w · Published: December 8, 2022

Spinal Cord Injury Oncology Research Methodology & Design

Simple Explanation

This study looked at using radiation to treat cancer that was pressing on the spinal cord in people who had already received radiation to that area before. The goal was to see if this re-irradiation was safe and effective. The study found that re-irradiation can help to stabilize or improve the ability to walk in these patients. However, there is a risk of developing a condition called radiation-induced myelopathy (RIM), which can damage the spinal cord. The researchers concluded that re-irradiation can be a useful treatment option, but careful consideration must be given to the risks and benefits, especially regarding the total dose of radiation given to the spinal cord.

Study Duration

8 Years (01/2008–09/2016)

Participants

22 patients with malignant spinal cord compression

Evidence Level

Level II, Phase II Clinical Trial

Key Findings

1
Re-irradiation is an effective treatment for MSCC, with 81.8% of evaluable patients experiencing stable or improved mobility at 5 weeks post-treatment.
2
There is a risk of radiation-induced myelopathy (RIM) with a cumulative dose of 120 Gy2; one patient (12.5% of evaluable patients) developed RIM.
3
Median survival time was 2.2 months, highlighting the palliative nature of the treatment and the advanced disease stage of the patients.

Research Summary

This phase II clinical trial evaluated the efficacy and toxicity of primary re-irradiation for malignant spinal cord compression (MSCC) using a biologically effective dose-based approach. The study found that re-irradiation can be an effective treatment for MSCC, with a majority of patients experiencing stable or improved mobility. However, the study also highlighted the risk of radiation-induced myelopathy (RIM) with higher cumulative doses, emphasizing the need for careful dose planning and risk assessment.

Practical Implications

Treatment Strategy

Re-irradiation can be considered as a viable treatment option for patients with MSCC at previously irradiated sites when surgery is not an option.

Dose Planning

Careful dose planning and consideration of cumulative biologically effective dose (BED) are crucial to minimize the risk of radiation-induced myelopathy (RIM).

Patient Selection

Patient selection for re-irradiation should consider factors such as the time interval since previous RT, cumulative BED, and individual risk factors for RIM.

Study Limitations

1
Small sample size (22 patients enroled, 11 evaluable for the primary outcome) limits the statistical power and generalizability of the findings.
2
Poor accrual and shorter-than-anticipated overall survival impacted the estimation of late toxicities.
3
Lack of radiotherapy quality assurance (RTQA) protocol and use of 2D/3D planning without detailed dose distribution analysis may affect the accuracy of dose estimates.

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