Image-Guided Robotic Radiosurgery for the Management of Intramedullary Spinal Cord Metastases-A Multicenter Experience

[Stereotactic high-dose irradiation for intramedullary metastases]

Intramedullary metastases (IMM) lead to severe neurological symptoms. They are extremely rare in clinical practice. Optimal management of such patients is not clearly defined. Surgery, chemo- and radiotherapy are the main options.

OBJECTIVE

To study the results of stereotactic high-dose irradiation for IMM considering local control of metastases, neurological status and life expectancy.

MATERIAL AND METHODS

Nineteen patients with 29 IMMs underwent high-dose irradiation (Cyber Knife G4 and TrueBeam STx devices) between 2016 and 2022. There were 1-10 fractions, radiation dose 14.0-35.0 Gy with isodose 70-100%. Local control and new spinal cord metastases were assessed using contrast-enhanced MRI. Clinical status and neurological functions were assessed using the Karnofsky and McCormick scales.

RESULTS

Local control rates were 91% and 78% after 6 and 12 months, respectively. Overall survival after treatment was 7.3 months, 6- and 12-month overall survival - 58% and 37%, respectively. In addition, 8 patients were available for follow-up. Of these, 6 ones demonstrated improvement or stabilization of neurological function after treatment. The main cause of death was progression of the underlying disease. No significant treatment-related toxic effects were observed.

CONCLUSION

High-dose irradiation is a safe, effective and time-saving treatment for IMM. Considering unadvisable surgical methods and chemotherapy for this pathology, we can recommend high-dose irradiation for patients with spinal cord metastases.

Influence of the Hypersensitivity to Low Dose Phenomenon on the Tumor Response to Hypofractionated Stereotactic Body Radiation Therapy

Stereotactic body radiation therapy (SBRT) has made the hypofractionation of high doses delivered in a few sessions more acceptable. While the benefits of hypofractionated SBRT have been attributed to additional vascular, immune effects, or specific cell deaths, a radiobiological and mechanistic model is still needed. By considering each session of SBRT, the dose is divided into hundreds of minibeams delivering some fractions of Gy. In such a dose range, the hypersensitivity to low dose (HRS) phenomenon can occur. HRS produces a biological effect equivalent to that produced by a dose 5-to-10 times higher. To examine whether HRS could contribute to enhancing radiation effects under SBRT conditions, we exposed tumor cells of different HRS statuses to SBRT. Four human HRS-positive and two HRS-negative tumor cell lines were exposed to different dose delivery modes: a single dose of 0.2 Gy, 2 Gy, 10 × 0.2 Gy, and a single dose of 2 Gy using a non-coplanar isocentric minibeams irradiation mode were delivered. Anti-γH2AX immunofluorescence, assessing DNA double-strand breaks (DSB), was applied. In the HRS-positive cells, the DSB produced by 10 × 0.2 Gy and 2 Gy, delivered by tens of minibeams, appeared to be more severe, and they provided more highly damaged cells than in the HRS-negative cells, suggesting that more severe DSB are induced in the "SBRT modes" conditions when HRS occurs in tumor. Each SBRT session can be viewed as hyperfractionated dose delivery by means of hundreds of low dose minibeams. Under current SBRT conditions (i.e., low dose per minibeam and not using ultra-high dose-rate), the response of HRS-positive tumors to SBRT may be enhanced significantly. Interestingly, similar conclusions were reached with HRS-positive and HRS-negative untransformed fibroblast cell lines, suggesting that the HRS phenomenon may also impact the risk of post-RT tissue overreactions.

Intramedullary spinal cord metastases from non-small cell lung carcinoma (NSCLC) associated with carcinomatous meningitis: a case report

Background:

Carcinomatous meningitis with metastases to the spinal cord [intramedullary spinal cord (IMSC)] is very rare, and a quick intervention to management of these patients is important in preventing neurological deterioration.

Methods:

We report a case of IMSC metastases from a stage IV non-small cell lung carcinoma in a 57-year-old man who presented with Brown-Sequard syndrome along with multiple brain metastases with associated carcinomatous meningitis and managed with urgent palliative external beam radiation therapy.

Conclusion:

A quick, short course of palliative radiation therapy for inoperable patients with IMSC metastases provides improvement in neurological function in the management of these oncologic emergencies in patients with short survival times.

Stereotactic body radiotherapy for intramedullary metastases: a retrospective series at the Oscar Lambret center and a systematic review

BACKGROUND

Intramedullary metastasis (IMM) is a rare disease with poor prognosis. The incidence of IMMs has increased, which has been linked to improved systemic treatment in many cancers. Surgery and/or radiotherapy are the most commonly used treatments; only small-sample retrospective studies and case reports on stereotactic body radiotherapy (SBRT) have reported acceptable results in terms of local control and clinical improvement, with no reported toxicity. Thus, we performed this monocentric retrospective study on five cases treated with SBRT for IMMs, which we supplemented with a systematic review of the literature.

METHODS

We included all patients treated for IMM with SBRT. The target tumor volume, progression-free survival, prescription patterns in SBRT, survival without neurological deficit, neurological functional improvement after treatment, and overall survival were determined.

RESULTS

Five patients treated with a median dose of 30 Gy in a median number of fractions of 5 (prescribed at a median isodose of 86%) included. The median follow-up duration was 23 months. Two patients showed clinical improvement. Three patients remained stable. Radiologically, 25% of patients had complete response and 50% had stable disease. No significant treatment-related toxicity was observed.

CONCLUSION

SBRT appears to be a safe, effective, and rapid treatment option for palliative patients.