Re-irradiation of Vertebral Body Metastases: Treatment in the Radiosurgery Era

A multi-centre retrospective study of long-term outcomes of spinal re-irradiation with SABR

INTRODUCTION

Stereotactic ablative body radiotherapy (SABR) is a highly conformal technique utilising a high dose per fraction commonly employed in the re-treatment of spinal metastases. This study sought to determine the safety and efficacy of re-irradiation with SABR to previously treated spinal metastases.

METHODS

This was a retrospective analysis of patients at three Australian centres who have undergone spinal SABR after previous spinal radiotherapy to the same or immediately adjacent vertebral level. Efficacy was determined in terms of rates of local control, while safety was characterised by rates of serious complications.

RESULTS

Thirty-three spinal segments were evaluated from 32 patients. Median follow-up for all patients was 2.6 years, and median overall survival was 4.3 years. Eleven of 33 (33.3%) treated spinal segments had local progression, with a local control rate at 12 months of 71.4% (95% C.I. 55.2%-92.4%). Four patients (16.7%) went on to develop cauda equina or spinal cord compression. Thirteen out of 32 patients (40.6%) experienced acute toxicity, of which 12 were grade 2 or less. Five out of 30 spinal (16.7%) segments with follow-up imaging had a radiation-induced vertebral compression fracture. There was one case of radiation myelitis which occurred in a patient who had mediastinal radiotherapy with a treatment field which overlapped their prior spinal radiation.

CONCLUSION

The patients in this study experienced long median survival, durable tumour control and high rates of freedom from long-term sequelae of treatment. These results support the use of SABR in patients who progress in the spine despite previous radiotherapy.

30 Gy in 4 Stereotactic Body Radiotherapy Fractions for Complex Spinal Metastases: Mature Outcomes Supporting This Novel Regimen

BACKGROUND AND OBJECTIVES

We designed a 30 Gy in 4 fractions stereotactic body radiotherapy protocol, as an alternative option to our standard 2-fraction approach, for primarily large volume, multilevel, or previously radiated spinal metastases. We report imaging-based outcomes of this novel fractionation scheme.

METHODS

The institutional database was reviewed to identify all patients who underwent 30 Gy/4 fractions from 2010 to 2021. Primary outcomes were magnetic resonance-based vertebral compression fracture (VCF) and local failure per treated vertebral segment.

RESULTS

We reviewed 245 treated segments in 116 patients. The median age was 64 years (range, 24-90). The median number of consecutive segments within the treatment volume was 2 (range, 1-6), and the clinical target volume (CTV) was 126.2 cc (range, 10.4-863.5). Fifty-four percent had received at least 1 previous course of radiotherapy, and 31% had previous spine surgery at the treated segment. The baseline Spinal Instability Neoplastic Score was stable, potentially unstable, and unstable for 41.6%, 51.8%, and 6.5% of segments, respectively. The cumulative incidence of local failure was 10.7% (95% CI 7.1-15.2) at 1 year and 16% (95% CI 11.5-21.2) at 2 years. The cumulative incidence of VCF was 7.3% (95% CI 4.4-11.2) at 1 year and 11.2% (95% CI 7.5-15.8) at 2 years. On multivariate analysis, age ≥68 years ( P = .038), CTV volume ≥72 cc ( P = .021), and no previous surgery ( P = .021) predicted an increased risk of VCF. The risk of VCF for CTV volumes <72 cc/≥72 cc was 1.8%/14.6% at 2 years. No case of radiation-induced myelopathy was observed. Five percent of patients developed plexopathy.

CONCLUSION

30 Gy in 4 fractions was safe and efficacious despite the population being at increased risk of toxicity. The lower risk of VCF in previously stabilized segments highlights the potential for a multimodal treatment approach for complex metastases, especially for those with a CTV volume of ≥72 cc.

Stereotactic Body Radiation Therapy for Spine Metastases-Findings from an Australian Population-Based Study

Background: To evaluate the use of stereotactic body radiation therapy (SBRT) for spine metastases and the associated factors in Australia. Methods: The Victorian Radiotherapy Minimum Dataset, which captures all episodes of radiotherapy delivered in the state of Victoria, was accessed to evaluate the patterns and trends of SBRT for spine metastases. The primary outcome was SBRT use and associated factors. Results: There were 6244 patients who received 8861 courses of radiotherapy for spine metastases between 2012 and 2017. Of these, 277 (3%) courses were SBRT, which increased from 0.4% in 2012 to 5% in 2017 (P-trend < 0.001). There was a higher proportion of SBRT use in patients with prostate cancer (6%) and melanoma (4%) compared to other cancers (2-3%) (p < 0.001). Patients from the highest socioeconomic quintiles (5%) were more likely to be treated with SBRT compared to patients from the lowest socioeconomic quintiles (3%) (p < 0.001). There was a higher proportion of SBRT use in private radiotherapy centres (6%) compared to public radiotherapy centres (1%) (p < 0.001). No spine SBRT was delivered in regional centres. In multivariate analyses, the year of treatment, age, primary cancers and radiotherapy centres were independently associated with SBRT use. Conclusion: This is the first Australian population-based study quantifying the increasing use of spine SBRT; however, the overall use of spine SBRT remains low. We anticipate an ongoing increase in spine SBRT, as spine SBRT gradually becomes the standard-of-care treatment for painful spine metastases.

Re-irradiation for intra-thoracic tumours and extra-thoracic breast cancer: dose accumulation, evaluation of efficacy and toxicity based on a literature review

The improvement seen in the diagnostic procedures and treatment of thoracic tumours means that patients have an increased chance of longer overall survival. Nevertheless, we can still find those who have had a recurrence or developed a secondary cancer in the previously treated area. These patients require retreatment including re-irradiation. We have reviewed the published data on thoracic re-irradiation, which shows that some specific healthy tissues can tolerate a significant dose of irradiation and these patients benefit from aggressive treatment; however, there is a risk of damage to normal tissue under these circumstances. We analysed the literature data on re-irradiation in the areas of vertebral bodies, spinal cord, breast, lung and oesophagus. We evaluated the doses of primary and secondary radiotherapy, the treatment techniques, as well as the local control and median or overall survival in patients treated with re-radiation. The longest OS is reported in the case of re-irradiation after second breast-conserving therapy where the 5-year OS range is 81 to 100% and is shorter in patients with loco-reginal re-irradiation where the 5-y OS range is 18 to 60%. 2-year OS in patients re-irradiated for lung cancer and oesophagus cancer range from 13 to 74% and 18 to 42%, respectively. Majority grade ≥3 toxicity after second breast-conserving therapy was fibrosis up to 35%. For loco-regional breast cancer recurrences, early toxicity occurred in up to 33% of patients resulting in mostly desquamation, while late toxicity was recorded in up to 23% of patients and were mostly ulcerations. Early grade ≥3 lung toxicity developed in up to 39% of patients and up to 20% of Grade 5 hemoptysis. The most frequently observed early toxicity grade ≥3 in oesophageal cancer was oesophagitis recorded in up to 57% of patients, followed by hematological complications which was recorded in up to 50% of patients. The most common late complications included dysphagia, recorded in up to 16.7% of patients. We have shown that thoracic re-irradiation is feasible and effective in achieving local control in some patients. Re-irradiation should be performed with maximum accuracy and care using the best available treatment methods with a highly conformal, image-guided approach. Due to tremendous technological progress in the field of radiotherapy, we can deliver radiation precisely, shorten the overall treatment time and potentially reduce treatment-related toxicities.

Image-Guided Robotic Radiosurgery for the Treatment of Same Site Spinal Metastasis Recurrences

Background

Due to recent medical advancements, patients suffering from metastatic spinal disease have a prolonged life expectancy than several decades ago, and some will eventually experience relapses. Data for the retreatment of spinal metastasis recurrences occurring at the very same macroscopic spot as the initially treated lesion are limited. Previous studies mainly included recurrences in the boundary areas as well as other macroscopic parts of the initially affected vertebrae. This study exclusively analyzes the efficacy and safety of spinal reirradiation for recurrences on the same site utilizing single-session robotic radiosurgery.

Materials and Methods

Patients between 2005 and 2020 who received radiotherapy for a spinal metastasis suffering from a local recurrence were eligible for analysis. Only patients undergoing a single-session reirradiation were included. All recurrences must have been occurred in the same location as the initial lesion. This was defined as a macroscopic recurrence on computed tomography occurring at the same site as the initial spinal metastasis. All other lesions, including those in the boundary areas or other parts of the initially affected vertebrae, were excluded.

Results

Fifty-three patients with fifty-three lesions were retreated for spinal metastases. The median dose and number of fractions for the initial radiotherapy were 36 Gy and 15, respectively. Eleven patients were initially treated with stereotactic body radiotherapy. Retreatment was performed with a median dose of 18 Gy prescribed to a median isodose of 70%. The local control was 77% after a median follow-up of 22.2 months. Patients experiencing a second recurrence received a lower dose (p = 0.04), mostly below 18 Gy, and had a worse coverage (p = 0.01) than those showing local tumor control. 51% of patients experienced an improvement in pain control after treatment delivery. Besides, four vertebral compression fractures (7% of patients) but no other adverse events higher than grade 2 were observed.

Conclusion

Single-session robotic radiosurgery appears to be a safe, time-saving, and effective treatment modality for spinal metastasis recurrences occurring in the same initial location if a considerable dose and coverage can be applied. Treatment results are comparable to reirradiated metastases in the boundary areas.

Stereotactic Ablative Radiotherapy for the Management of Spinal Metastases: A Review

Importance

Rising cancer incidence combined with improvements in systemic and local therapies extending life expectancy are translating into more patients with spinal metastases. This makes the multidisciplinary management of spinal metastases and development of new therapies increasingly important. Spinal metastases may cause significant pain and reduced quality of life and lead to permanent neurological disability if compression of the spinal cord and/or nerve root occurs. Until recently, treatments for spinal metastases were not optimal and provided temporary local control and pain relief. Spinal stereotactic ablative radiotherapy (SABR) is an effective approach associated with an improved therapeutic ratio, with evolving clinical application.

Objective

To review the literature of spinal SABR for spinal metastases, discuss a multidisciplinary approach to appropriate patient selection and technical considerations, and summarize current efforts to combine spinal SABR with systemic therapies.

Evidence Review

The MEDLINE database was searched to identify articles reporting on spinal SABR to September 30, 2018. Articles including clinical trials, prospective and retrospective studies, systematic reviews, and consensus recommendations were selected for relevance to multidisciplinary management of spinal metastases.

Results

Fifty-nine unique publications with 5655 patients who underwent SABR for spinal metastases were included. Four comprehensive frameworks for patient selection were discussed. Spinal SABR was associated with 1-year local control rates of approximately 80% to 90% in the de novo setting, greater than 80% in the postoperative setting, and greater than 65% in the reirradiation setting. The most commonly discussed adverse effect was development of a vertebral compression fracture with variable rates, most commonly reported as approximately 10% to 15%. High-level data on the combination of SABR with modern therapies are still lacking. At present, 19 clinical trials are ongoing, mainly focusing on combined modality therapies, radiotherapy prescription dose, and oligometastic disease.

Conclusions and Relevance

These findings suggest that spinal SABR may be an effective treatment option for well-selected patients with spinal metastases, achieving high rates of local tumor control with moderate rates of adverse effects. Optimal management should include review by a multidisciplinary care team.

Outcomes after reirradiation of spinal metastasis with stereotactic body radiation therapy (SBRT): a retrospective single institutional study

This study was aimed at assessing the feasibility and toxicity of using stereotactic body radiation therapy (SBRT) for reirradiation of spinal metastatic tumors. We conducted a retrospective review, from our institutional database, of the data of patients who received reirradiation, with overlap of some prescribed isodose lines to the vertebra from the initial radiation therapy, between 2007 and 2019. We identified 40 patients with spinal metastatic tumors, of whom 2 had 2 metastatic vertebral lesions each, totaling up to 42 target lesions. The median dose to spinal cord at the initial radiation therapy was 30 Gy. SBRT based on the intensity-modulated radiation therapy (IMRT) technique was used for reirradiation to spare the spinal cord. All patients received a prescription dose of 25 Gy in 5 fractions to the planning target volume (PTV). Among the 40 cases who had pain, pain relief was obtained in 24 (60%) after reirradiation. Neurologic improvement was obtained in 8 of 15 cases (53%). The adverse events were evaluated using the Common Terminology Criteria for Adverse Events Version 5.0. Reirradiation was well-tolerated, with only 2 patients experiencing adverse events ≥grade 2 in severity, including 1 patient with grade 3 pain, and another patient with grade 3 spinal fracture. None of the patients developed radiation myelopathy. Our data demonstrated that reirradiation of spinal metastasis using SBRT provided effective pain relief and neurologic improvement, with minimal toxicity.

Re-irradiation of vertebral bodies

Improvements in clinical care and therapy mean that more patients are diagnosed and living longer with vertebral metastases. Thus, they are at risk of the development of recurrence that requires re-irradiation. Normal tissues often recover some of the damage caused by the primary radiotherapy with time and specific normal tissues can tolerate a considerable retreatment radiation dose. However, the risk of normal tissue damage and the impact on the quality of life must be considered and should be done with maximum care and accuracy especially in the vertebral area. For many years conventional external beam radiation therapy was the standard treatment modality. Fortunately, with crucial technological progress in the field of radiation oncology we are able to integrate body imaging with accurate treatment delivery methods as stereotactic body radiotherapy to improve the efficacy, shorten the overall treatment time and potentially reduce treatment-related toxicities. A short description of re-irradiation strategy covering diagnostic procedures, volume delineation, dose reconstructions, treatment planning, and guidelines are outlined. Moreover, publications on vertebral bodies re-irradiation summarizing available knowledge about toxicity, dose-volume constraints, local control, and pain response are followed. Although the knowledge is limited to a series of a single institution, it shows that re-irradiation is an effective treatment for local control and pain response. Furthermore, treatment was also shown to be safe with low risk of spinal cord damage which is one of the most worrisome toxicity.

Stereotactic Body Radiotherapy for Spinal Metastases at the Extreme Ends of the Spine: Imaging-Based Outcomes for Cervical and Sacral Metastases

Background

The unique anatomy and biomechanical features of the cervical spine and sacrum may impact treatment outcomes following spine stereotactic body radiotherapy (SBRT). Current data for spine metastases are not specific for these locations.

Objective

To report imaging-based SBRT outcomes to cervical and sacral metastases.

Methods

We retrospectively reviewed our prospective spine SBRT database for cervical and sacral metastases. Patients were followed at 2- to 3-mo intervals with a clinical visit and full spine magnetic resonance imaging (MRI) and we report overall survival (OS), vertebral compression fracture (VCF), and MR imaging-based local control (LC) rates.

Results

Fifty-two patients and 93 treated spinal segments were identified. Fifty-six segments were within the cervical spine and 37 within the sacrum, the median follow-up was 14.4 and 19.5 mo, and the median total dose/number of fractions was 24 Gy/2, respectively. Cumulative LC at 1 and 2 yr were 94.5% and 92.7% for the cervical cohort, and 86.5% and 78.7% in the sacral cohort, respectively. Lack of posterior spinal element involvement in the cervical spine (P < .0001) and absence of epidural disease (hazard ratio 0.275, 95% confidence interval 0.076-0.989, P = .048) in the sacral cohort predicted LC. Median OS was 16.3 and 28.5 mo in the cervical spine and sacrum cohorts, respectively. Two cases of sacral VCF, 1 brachial plexopathy, and 1 lumbar-sacral plexopathy were observed.

CONCLUSION

Although high rates of LC were observed, strategies specific to the sacrum may require further optimization.

Second Re-irradiation: Clinical Examples of Worthwhile Treatment

INTRODUCTION

 Improved treatment approaches have resulted in longer survival of patients with certain types of incurable cancer, without eliminating the need for symptom palliation and supportive measures. In this context, re-irradiation is an increasingly important option. Little data exists about a second or repeat re-irradiation.

METHODS

From a single institution database, patients who received a second re-irradiation with cumulative equivalent doses (equivalent dose in 2-Gy fractions (EQD2) for late effects, alpha/beta-value 3 Gy) of more than 90 Gy and survived for more than six months were identified. Illustrative clinical examples were provided.

RESULTS

The examples describe the treatment of sacral bone metastases, recurrent rectal cancer, and pelvic lymph node metastases. The maximum cumulative EQD2 was 142 Gy. Symptomatic responses were obtained without clinically relevant side effects.

CONCLUSION

 These three cases illustrate that a second re-irradiation has the potential to provide worthwhile palliative effects without causing overt late toxicity during the remaining life time. In patients who tolerated previous radiotherapy well, further re-irradiation may contribute to the ever-increasing armamentarium of options that increase the survival of patients with incurable cancer and try to prolong the time period where independent living is possible.