Spine Stereotactic Body Radiotherapy for Prostate Cancer Metastases and the Impact of Hormone Sensitivity Status on Local Control

Stereotactic body radiation therapy for spinal metastases from gastrointestinal primary cancers

PURPOSE

Metastases from gastrointestinal (GI) primary cancers are considered relatively radioresistant. This study is one of the largest to evaluate outcomes following stereotactic body radiation therapy (SBRT) for GI cancer spinal metastases and supplements its findings with a review of the literature.

METHODS

A prospectively maintained single-institution database of spinal metastases treated with SBRT was analyzed. Seventy-five patients with 106 GI primary cancer spinal metastases were identified. The median single-fraction dose was 16 Gy (interquartile range (IQR): 14-16). Multi-fraction regimens ranged from 18 to 35 Gy over 2-5 fractions.

RESULTS

Median follow-up was 5 months (IQR: 1-13). Cumulative incidence rates of 3-, 6-, and 12-month local failure (LF) were 5%, 9%, and 10%, respectively. Rates of 12-month LF were 6% for gastroesophageal, 10% for hepatobiliary, and 13% for colorectal cancers. Multilevel tumors ≥ 2 vertebrae were associated with LF (p = 0.006, HR: 5.61, 95% CI: 1.61-19.5). Rates of 3-, 6-, and 12-month overall survival (OS) were 68%, 50%, and 41%, respectively. Multivariable analysis showed epidural disease associated with inferior OS (p = 0.037, HR: 1.75, 95% CI: 1.04-2.96). Complete or partial pain responses for 93 tumors (88%) presenting with pain were 60%, 51%, 32%, and 32% after 1, 3, 6, and 12 months, respectively. Ten vertebral compression fractures (9%) developed following treatment. Twelve radiation toxicities (11%) were observed, with no cases of neuropathy or myelopathy.

CONCLUSIONS

SBRT offers effective local tumor control and pain palliation with minimal toxicity for GI cancer spinal metastases, whose incidence is expected to rise with advances in screening and systemic therapies.

Breast cancer spine metastases treated with stereotactic body radiation therapy: patient outcomes and predictors

BACKGROUND/PURPOSE

Spine stereotactic body radiation therapy (SBRT) is increasingly utilized for oligometastatic and symptomatic breast cancer spinal metastases (BCSM), yet primary site-specific outcomes remain lacking. This study evaluates outcomes of SBRT for BCSM, focusing on predictors of local failure (LF), vertebral compression fraction (VCF) and overall survival (OS).

MATERIALS/METHODS

We retrospectively analyzed 409 BCSM in 168 patients treated with SBRT between 2008 and 2022. Receptor status was grouped based on ER+/Her2-, HER2+, and ER-/HER2-. Follow-up included full-spine magnetic resonance imaging (MRI) and clinical assessment every 3-6 months post-SBRT. The primary endpoint was radiological LF, and secondary endpoints were OS and VCF.

RESULTS

Median follow-up was 33 months (range, 3.3-123 months), most were ECOG 0-1 (95%), neurologically intact (94%), polymetastatic (> 5 metastases, 45%), and ER+/HER2- (79%). Of 409 segments, most had no prior radiation or surgery (76%), were SINS stable (60%) and treated with 24-28 Gy/2 fractions (73%). Five-year LF, OS and VCF rates were 14%, 45% and 11%, respectively. On multivariable analyses, lower LF rates were associated with < 2 lines of prior systemic therapy, low/no grade epidural disease, and greater equivalent dose in 2 Gy fractions (α/β = 2) to the spinal cord/thecal sac (HR = 0.97 per 1 Gy increase, 95% CI: 0.949-0.995, p = 0.019). ER-/HER2-, liver and lung metastases, and > 2 systemic therapy lines predicted worse OS. Baseline VCF and deformity were associated with a higher VCF risk.

CONCLUSION

Treatment intensification in those heavily systemically pretreated or with high-grade epidural disease may optimize long-term LF rates independent of molecular status.

Overview of Molecular Prognostication for Common Solid Tumor Histologies - What the Surgeon Should Know

STUDY DESIGN

Narrative Literature review.

OBJECTIVE

To provide a general overview of important molecular markers and targeted therapies for the most common neoplasms (lung, breast, prostate and melanoma) that metastasize to the spine and offer guidance on how to best incorporate them in the clinical setting.

METHODS

A narrative review of the literature was performed using PubMed, Google Scholar, Medline databases, as well as the histology-specific National Comprehensive Cancer Network guidelines to identify relevant articles limited to the English language. Relevant articles were reviewed for commonly described molecular mutations or targeted therapeutics, as well as associated clinical outcomes, and surgery-related risks.

RESULTS

Molecular markers and targeted therapies have dramatically improved the survival of cancer patients. The increasing importance of prognostic molecular markers and targeted therapies provides rationale for their incorporation into clinical decision-making for patients diagnosed with metastatic spine disease. In this review, we discuss the molecular markers/mutations and targeted therapies associated with the most common malignancies that metastasize to the spine and provide a framework that the surgeon can utilize when evaluating patients for potential intervention. Finally, we provide case examples that highlight the importance of molecular prognostication and therapies in surgical decision-making.

CONCLUSION

An integrated understanding of the implications of surgery, radiation, molecular markers and targeted therapies that guide prognostication and treatment is warranted in order to achieve the most favorable outcomes for patients with metastatic spine disease.

Advanced Radiotherapy Technologies in Spine Tumors: What the Surgeon Needs to Know

STUDY DESIGN

Narrative review of existing literature.

OBJECTIVES

Significant technological advancements in radiotherapy planning and delivery have enabled new radiotherapy techniques for the management of spine tumors. The objective of this study was to provide a comprehensive summary of these treatment techniques for practicing spine surgeons.

METHODS

A narrative review of the existing literature on stereotactic body radiation therapy (SBRT) and particle beam therapy (PBT) for the treatment of spine tumors was performed. The characteristics, implementation and evidence supporting these strategies in the management of primary spinal neoplasms were summarized.

RESULTS

The clinical effectiveness of SBRT for the control and symptom palliation of metastatic spinal tumors are well demonstrated in multiple clinical trials. Risks such as fracture, radiculopathy and plexopathy exist after spine SBRT, necessitating an individualized approach in a well experienced multidisciplinary setting. SBRT should be considered a key component of a well-rounded treatment plan for metastatic spine tumors in combination with surgery, vertebral augmentation, and drug therapy, where indicated, to achieve optimal patient outcomes. Additionally, PBT and SBRT are also leading to promising results for primary spine tumors, though comparative effectiveness studies and prospective clinical trials are required to establish these modalities more formally as alternatives to conventionally fractionated photon radiotherapy.

CONCLUSIONS

SBRT and PBT are emerging as effective and well tolerated treatment options for primary and metastatic spine tumors. Additional investigation is needed to personalize these treatment options and further strengthen these approaches as key components in a multidisciplinary approach to the management of spinal neoplasms.

Radiosurgery Society Case-Based Guide to Stereotactic Body Radiation Therapy for Challenging Cases of Spinal Metastases

PURPOSE

Spinal stereotactic body radiation therapy (SBRT) has become the standard of care in management of patients with limited sites of metastatic disease, radioresistant histologies, painful vertebral metastases with long life expectancy and cases of reirradiation. Our case-based guidelines aim to assist radiation oncologists in the appropriate utilization of SBRT for common, yet challenging, cases of spinal metastases.

METHODS AND MATERIALS

Cases were selected to include scenarios of large volume sacral disease with nerve entrapment, medically inoperable disease abutting the thecal sac, and local failure after prior SBRT. Relevant literature was reviewed, and areas requiring further investigation were discussed to offer a framework for evidence-based clinical practice.

RESULTS

Spinal SBRT can be effectively delivered in challenging cases following multidisciplinary discussion by using a methodical approach to patient selection, appropriate dose selection, and adherence to evidence-based dose constraints.

CONCLUSIONS

The Radiosurgery Society's case-based practice review offers guidance to practicing physicians treating technically challenging SBRT candidate patients with spinal metastases.

Radiation therapy, radiosurgery, chemotherapy and targeted therapies for metastatic spine tumors: WFNS Spine committee recommendations

OBJECTIVE

This review aims to formulate the most current, evidence-based recommendations regarding radiation therapy, radiosurgery, and chemotherapy for patients with metastatic spine tumors.

METHODS

A systematic literature using PRISMA methodology was performed from 2010-2023 using the search terms "radiosurgery," "radiation therapy," "external beam radiation therapy," or "stereotactic body radiation therapy" in conjunction with "spinal," "spine," "metastasis," "metastases," or "metastatic."

RESULTS

Spinal metastases should be managed in a multidisciplinary team consisting of spine surgeons, radiation oncologists, radiologists and oncologists. Patients identified as potential candidates for SRS/EBRT using internationally recognized frameworks and criteria should be assessed by surgeons to see if surgical cyto-reduction/ separation surgery can be achieved. Choices for treatment of recurrence include re-irradiation with SBRT vs EBRT, surgical debulking, additional chemotherapy or palliative care. There is a lack of current clinical evidence to support the routine use of targeted therapies in the management of metastatic spinal tumors.

CONCLUSIONS

Improving the management of spinal metastasis will lead to increased quality of life and improved survival. This review provides current, evidence-based guidelines on radiation therapy, radiosurgery, and chemotherapy for patients with metastatic spine tumors.

Stereotactic radiosurgery for patients with spinal metastases from prostate cancer

PURPOSE

Spinal metastases may result in intractable pain, neurological deficit, and vertebral body collapse. There are only a few studies describing outcomes following spine stereotactic radiosurgery (SRS) specifically for prostate cancer metastases.

METHODS

A prospectively collected database of patients with prostate cancer spinal metastases treated at the University of Pittsburgh Medical Center from 2003 to 2023 was analyzed. The primary outcome was local control (LC). Secondary outcomes were overall survival (OS), pain resolution, and adverse radiation effects (AREs).

RESULTS

Thirty-seven patients and 51 lesions were identified. Fifteen lesions (29%) were previously resected and 34 lesions (67%) were previously irradiated. The median tumor volume was 37.0 cc (range: 2.9-263.3). A majority of lesions (71%) were treated in a single fraction (median 20 Gy, range: 14-22.5); multi-fractionated treatment consisted of 21-30 Gy in 2-5 fractions. Median follow-up was 12 months (range: 1-146). The 6-month, 1-year, and 2-year LC rates were 97%, 91%, and 91%, respectively. No tested prognostic factors were associated with LC, including hormone sensitivity. The 6-month, 1-year, and 2-year OS rates were 71%, 56%, and 32%; age > 70 years (p = 0.048) and tumor volume > 30 cc (p = 0.03) were associated with inferior rates of OS. Complete or partial pain response was observed in 58% of patients. There were 8 instances (16%) of AREs, 2 of which were vertebral compression fractures (4%).

CONCLUSION

Radiosurgery as a primary or adjuvant treatment modality for prostate cancer spinal metastases confers durable LC and moderate pain relief with minimal toxicity. Further studies are warranted to optimize management in this patient population.

Stereotactic Body Radiation Therapy for Sacral Metastases: Deviation From Recommended Target Volume Delineation Increases the Risk of Local Failure

PURPOSE

Although spine stereotactic body radiation therapy (SBRT) is considered a standard of care in the mobile spine, mature evidence reporting outcomes specific to sacral metastases is lacking. Furthermore, there is a need to validate the existing sacral SBRT international consensus contouring guidelines to define the optimal contouring approach. We report mature rates of local failure (LF), adverse events, and the effect of contouring deviations in the largest experience to date specific to sacrum SBRT.

METHODS AND MATERIALS

Consecutive patients who underwent sacral SBRT from 2010 to 2021 were retrospectively reviewed. The primary endpoint was magnetic resonance imaging-based LF with a focus on adherence to target volume contouring recommendations. Secondary endpoints included vertebral compression fracture and neural toxicity.

RESULTS

Of the 215 sacrum segments treated in 112 patients, most received 30 Gy/4 fractions (51%), 24 Gy/2 fractions (31%), or 30 Gy/5 fractions (10%). Sixteen percent of segments were nonadherent to the consensus guideline with a more restricted target volume (undercontoured). The median follow-up was 21.4 months (range, 1.5-116.9 months). The cumulative incidence of LF at 1 and 2 years was 18.4% and 23.1%, respectively. In those with guideline adherent versus nonadherent contours, the LF rate at 1 year was 15.1% versus 31.4% and at 2 years 18.8% versus 40.0% (hazard ratio [HR], 2.5; 95% CI, 1.4-4.6; P = .003), respectively. On multivariable analysis, guideline nonadherence (HR, 2.4; 95% CI, 1.3-4.7; P = .008), radioresistant histology (HR, 2.4; 95% CI, 1.4-4.1; P < .001), and extraosseous extension (HR, 2.5; 95% CI, 1.3-4.7; P = .005) predicted for an increased risk of LF. The cumulative incidence of vertebral compression fracture was 7.1% at 1 year and 12.3% at 2 years. Seven patients (6.3%) developed peripheral nerve toxicity, of whom 4 had been previously radiated.

CONCLUSIONS

Sacral SBRT is associated with high efficacy rates and an acceptable toxicity profile. Adhering to consensus guidelines for target volume delineation is recommended to reduce the risk of LF.

Stereotactic Radiosurgery for Patients with Spinal Metastases from Thyroid Cancer: A 20-Year Experience

OBJECTIVE

Primary thyroid cancer metastasizing to the spine portends poor survival and low quality of life. Current management strategies continue to evolve. This single-institution retrospective study analyzes outcomes after spinal stereotactic radiosurgery for patients with spinal metastases from thyroid cancer.

METHODS

Nineteen patients (median age: 64.5 years) were treated with stereotactic radiosurgery (SRS) for spinal primary thyroid metastases (40 metastases, 47 vertebral levels) between 2003 and 2023. Nineteen (47.5%) lesions had epidural involvement and 20 (50%) lesions were classified as potentially unstable or unstable via the Spinal Instability Neoplastic Score. The median tumor volume per lesion was 33 cc (range: 1.5-153). The median single fraction prescription dose was 20 Gy (range: 12-23.5).

RESULTS

The median follow-up period was 15 months (range: 2-40). Five (12.8%) lesions locally progressed at a median of 9 months (range: 4-26) after SRS. The 1-, 2-, and 3-year local tumor control rates per lesion were 90.4%, 83.5%, and 75.9%, respectively. On univariate analysis, age at SRS >70 years (P = 0.05, hazard ratio: 6.86, 95% confidence interval: 1.01-46.7) was significantly correlated with lower rates of local tumor control. The median overall survival was 35 months (range: 2-141). The 1-, 2-, and 3-year overall survival rates were 73.7%, 50.4%, and 43.2%, respectively. For 33 lesions initially associated with pain, patients reported pain improvement (22 lesions, 66.7%), stability (10 lesions, 30.3%), and worsening (1 lesion, 3.0%) after SRS. One patient developed dysphagia 4 months after SRS treatment.

CONCLUSIONS

SRS can be utilized as an effective and safe primary and adjuvant treatment option for primary thyroid metastases to the spine.

The role of spine stereotactic radiosurgery for patients with breast cancer metastases

PURPOSE

Breast cancer that metastasizes to the spine is associated with low quality of life and poor survival. Radiosurgery has an increasing role in this patient population. This single-institution (2003-2023) study analyzes clinical outcomes and prognostic factors for patients who underwent spinal stereotactic radiosurgery (SSRS) for metastatic breast cancer.

METHODS

Ninety patients (155 unique breast cancer spinal metastases) were treated with SSRS. The median age was 57 years (range: 35-88), and the median KPS was 80 (range: 40-100). Forty-two (27%) lesions were managed surgically prior to radiosurgery. At SSRS, 75 (48%) lesions impinged or compressed the spinal cord per the epidural spinal cord scale (ESCC). Seventy-nine (51%) lesions were categorized as potentially unstable or unstable by the Spinal Instability Neoplastic Score (SINS).

RESULTS

The median follow-up was 15 months (range: 1-183). The median single-session tumor volume was 25.4 cc (range: 2-197), and the median single-fraction prescription dose was 17 Gy (range: 12-25). Seven (5%) lesions locally progressed. The 1-, 2-, and 5-year local control rates were 98%, 97%, and 92%, respectively. The median overall survival (OS) for the cohort was 32 months (range: 2-183). The 1-, 2-, and 5-year OS rates were 72%, 53%, and 30%, respectively. On univariate analysis, KPS ≥ 80 (p = 0.009, HR: 0.51, 95% CI: 0.31-0.84) was associated with improved OS. Patient-reported pain improved (68%), remained stable (29%), or worsened (3%) following radiosurgery. Fifteen (10%) radiation-induced toxicities were reported.

CONCLUSIONS

Spinal radiosurgery is a safe and highly effective long-term treatment modality for metastases to the spine that originate from breast cancer.

The Role of Stereotactic Radiosurgery in Patients With Brain Metastases From Colorectal Cancers

BACKGROUND AND OBJECTIVES

The role of stereotactic radiosurgery (SRS) in patients with brain metastases (BMs) from colorectal cancers (CRCs) has not been established. The authors present a single-institution experience of patients with CRC who underwent SRS with metastatic brain spread.

METHODS

We retrospectively analyzed 111 patients with metastatic CRC (64 female, 57.7%), with 449 BMs treated with Gamma Knife SRS between 2000 and 2022. The median age during SRS was 63 years (range: 28-86), and the median Karnofsky Performance Scale was 80 (range: 60-100). The primary sites were colon (85 patients, 76.6%) and rectal (26 patients, 23.4%). Three patients underwent hypofractionated SRS (3 sessions) with a median margin dose of 27 Gy (range: 27-30). All other patients underwent single-session SRS with a median margin dose of 18 Gy (range: 13-20).

RESULTS

The median patient survival after SRS was 7 months (range: 1-174). Ninety-eight (88.3%) patients expired at last follow-up and 15 patients (15.3%) died related to progressive intracranial disease. A Karnofsky Performance Scale of <80 at SRS presentation ( P = .02, hazard ratio [HR]: 0.6, 95% CI: 0.4-0.9) and no previous surgical resection ( P < .01, HR: 0.4, 95% CI: 0.3-0.7) were associated with inferior overall survival using multivariate analysis. Seventeen patients (15.3%) had documented local tumor progression after SRS, at a median time of 7 months (range: 3-34) between SRS and progression. Twenty-six patients (23.4%) developed new BMs at a median of 5 months (range: 2-26) between SRS and new tumor detection. Less than three BMs at SRS presentation ( P = .02, HR: 2.6, 95% CI: 1.2-5.6) were associated with better distant tumor control on multivariate analysis. The incidence of adverse radiation effects was 5.4%.

CONCLUSION

SRS effectively controls BMs from CRC with low risk of treatment-related toxicity. During follow-up, the development of additional metastases can be safely treated by repeat SRS.

A Cancer Care Ontario Consensus-Based Organizational Guideline for the Planning and Delivery of Spine Stereotactic Body Radiation Therapy Treatment in Ontario

The proposed recommendations are primarily based on the consensus opinion and in-field experience of the Ontario Health/Cancer Care Ontario stereotactic body radiation therapy (SBRT) for Spine Metastasis Guideline Development Group and published literature when available. Primary consideration was given to the perceived benefits for patients and the small likelihood of harm arising from recommendation implementation. Apart from the magnetic resonance imaging (MRI) follow-up strategy, all evidence was considered indirect and was provided by the working group in conjunction with their collective expertise in the field of SBRT. The application of an SBRT program requires a multidisciplinary team consisting of a radiation oncologist, spine surgeon, neuroradiologist, medical physicist, medical dosimetrist, and radiation therapist. In Canada, linear accelerators are the most used treatment delivery units and should follow technology-specific quality assurance procedures. Immobilization technique is location dependant. Treatment planning MRI sequences should be acquired no more than 14 days from the date of treatment. In the case of epidural disease, simulation MRI should be completed no more than 7 days from the date of treatment. After treatment, patients should be followed with routine clinical visits every 3 months for the first year, every 3 to 6 months during years 2 and 3, and every 4 to 6 months thereafter. The recommendations enclosed provide a framework for the minimum requirements for a cancer center in Ontario, Canada to offer SBRT for spine metastases.

Dose-Escalated 2-Fraction Spine Stereotactic Body Radiation Therapy: 28 Gy Versus 24 Gy in 2 Daily Fractions

PURPOSE

Stereotactic body radiation therapy (SBRT) for spine metastases improves pain response rates compared with conventional external beam radiation therapy; however, the optimal fractionation schedule is unclear. We report local control and toxicity outcomes after dose-escalated 2-fraction spine SBRT.

METHODS AND MATERIALS

A prospectively maintained institutional database of over 600 patients and 1400 vertebral segments treated with spine SBRT was reviewed to identify those prescribed 28 or 24 Gy in 2 daily fractions. The primary endpoint was magnetic resonance imaging based local failure (LF), and secondary endpoints included overall survival and vertebral compression fracture (VCF).

RESULTS

A total of 947 treated vertebral segments in 482 patients were identified, of which 301 segments in 159 patients received 28 Gy, and 646 segments in 323 patients received 24 Gy in 2 fractions. Median follow-up per patient was 23.5 months, and median overall survival was 49.1 months. In the 28 Gy cohort, the 6-, 12-, and 24-month cumulative incidences of LF were 3.5%, 5.4%, and 11.1%, respectively, versus 6.0%, 12.5%, and 17.6% in the 24 Gy cohort, respectively (P = .008). On multivariable analysis, 24 Gy (hazard ratio [HR], 1.525; 95% confidence interval, 1.039-2.238; P = .031), paraspinal disease extension (HR, 1.422; 95% confidence interval, 1.010-2.002; P = .044), and epidural extension in either radioresistant or radiosensitive histologies (HR, 2.117 and 1.227, respectively; P = .003) were prognostic for higher rates of LF. Risk of VCF was 5.5%, 7.6%, and 10.7% at 6, 12, and 24 months, respectively, and was similar between cohorts (P = .573). Spinal malalignment (P < .001), baseline VCF (P = .003), junctional spine location (P = .030), and greater minimum dose to 90% of planning target volume were prognostic for higher rates of VCF.

CONCLUSIONS

Dose escalation to 28 Gy in 2 daily fractions was associated with improved local control without increasing the risk of VCF. The 2-year local control rates are consistent with those predicted by the Hypofractionated Treatment Effects in the Clinic spine tumor control probability model, and these data will inform a proposed dose escalation randomized trial.

A quantitative and comparative evaluation of stereotactic spine radiosurgery local control: proposing a consistent measurement methodology

OBJECTIVE

Stereotactic body radiotherapy (SBRT) is a precise and conformal treatment modality used in the management of metastatic spine tumors. Multiple studies have demonstrated its safety and efficacy for pain and tumor control. However, no uniform quantitative imaging methodology exists to evaluate response to treatment in these patients. This study presents radiographic local control rates post-SBRT, systematically compares measurements acquired according to WHO and Response Evaluation Criteria in Solid Tumors (RECIST) criteria, and explores the relationship to patient outcome.

METHODS

The authors performed a retrospective review of prospectively obtained data from a cohort of 59 consecutive patients (81 metastatic isocenters) treated with SBRT and followed with serial MRI scans. Measurements were performed by a neuroradiologist blinded to the patients’ clinical course. Local control status was determined according to both WHO and RECIST measurements, and agreement between the measuring methodologies was calculated and reported.

RESULTS

Eighty-one isocenters (111 vertebral bodies) were treated with SBRT. The mean treatment dose was 13.96 Gy and the median follow-up duration was 10.8 months, during which 408 MRI scans were evaluated with both WHO and RECIST criteria for each scan point. Imaging demonstrated a mean unidimensional size decrease of 0.2 cm (p = 0.14) and a mean area size decrease of 0.99 cm2 (p = 0.03). Although 88% of the case classifications were concordant and the agreement was significant, WHO criteria were found to be more sensitive to tumor size change. The local control rates according to WHO and RECIST were 95% and 98%, respectively.

CONCLUSIONS

Although WHO volumetric measurements are admittedly superior for tumor size measurement, RECIST is simpler, reproducible, and for the first time is shown here to be comparable to WHO criteria. Thus, the application of RECIST methodology appears to be a suitable standard for evaluating post-SBRT treatment response. Moreover, using comprehensive and consistent measuring approaches, this study substantiates the efficacy of SBRT in the treatment of spine metastases.