High-dose, single-fraction image-guided intensity-modulated radiotherapy for metastatic spinal lesions

State of the art management in spine oncology: a worldwide perspective on its evolution, current state, and future

STUDY DESIGN

A review of the past and current status of the evolving field of spine oncology.

OBJECTIVE

To provide a framework of reference for developments in the field, particularly the rapidly evolving field of molecular biology, as well as contemporary practice in the management of spine tumors.

METHODS

Literature review of the surgical treatment of spine tumors in the past and present, the emerging radiologic and biologic technologies, as well as the field of targeted therapy in cancer and the economic implications of technological advances.

RESULTS

A vast contemporary literature is currently available that provides a clear rational basis for treatment. Most treatment recommendations are currently based on retrospective data and small Phase II prospective studies. Treatment paradigms continue to evolve without their relative merits being evaluated by randomized controlled trials. The current lack of randomized trials in spine oncology reflect both the rarity of spine tumors and strongly held biases based on retrospective studies and institutional bias.

CONCLUSION

Spine oncology is a rapidly evolving field with contributions in surgery, radiation therapy, and targeted chemotherapy resulting in overall improvement in quality of life and survival in patients with spine tumors. However, the economic consequences of these improvements are substantial and need to be kept in proper perspective.

Radiotherapy and radiosurgery for metastatic spine disease: what are the options, indications, and outcomes?

STUDY DESIGN

Systematic literature review.

OBJECTIVE

To determine the options, indications, and outcomes for conventional radiotherapy and radiosurgery for metastatic spine disease.

METHODS

Three research questions were determined through a consensus among a multidisciplinary panel of spine oncology experts. A systematic review of the literature was conducted regarding radiotherapy and radiosurgery for metastatic spine disease using PubMed, Embase, the Cochrane Evidence Based Medicine Database, and a review of bibliographies of reviewed articles.

RESEARCH QUESTIONS

1. What are the clinical outcomes of the current indications for conventional radiotherapy alone and stereotactic radiosurgery for metastatic spine disease? 2. What are the current dose recommendations and fractionation schedules for conventional spine radiotherapy and stereotactic radiosurgery for metastatic spine disease? 3. What are the current known patterns of failure and complications after conventional spine radiation and stereotactic radiosurgery for metastatic spine disease?

RESULTS

For conventional radiotherapy, the initial literature search yielded a total of 531 potentially relevant abstracts. Each of these abstracts was reviewed for relevance, and 62 were selected for in-depth review. Forty-nine studies met all the inclusion criteria. References from the articles included in the analysis and review articles were also examined for potential inclusion in the study. For conventional radiotherapy, 3 randomized trials (high-quality evidence), 4 prospective studies (moderate-quality evidence), and over 40 nonprospective data sets (low- or very-low-quality evidence) that included over 5000 patients in the literature were included in this review. Drawing from the same databases, a systematic search for radiosurgery yielded 195 abstracts, of which 29 met all inclusion criteria. They all represented single-institution reports (low- or very-low-quality data). No randomized data are available for spine radiosurgery.

CONCLUSION

A systematic review of the available evidence suggests that conventional radiotherapy is safe and effective with good symptomatic response and local control, particularly for radiosensitive histologies. A strong recommendation can be made with moderate quality evidence that conventional fractionated radiotherapy is an appropriate initial therapy option for patients with spine metastases in cases in which no relative contraindication exists. A systematic review of the available evidence suggests that radiosurgery is safe and provides an incremental benefit over conventional radiotherapy with more durable symptomatic response and local control independent of histology, even in the setting of prior fractionated radiotherapy. A strong recommendation can be made with low-quality evidence that radiosurgery should be considered over conventional fractionated radiotherapy for the treatment of solid tumor spine metastases in the setting of oligometastatic disease and/or radioresistant histology.

Shifting paradigms in the treatment of metastatic spine disease

STUDY DESIGN

Systematic review and evidence appraisal.

OBJECTIVE

To evaluate the optimal treatment for patients with spinal cord compression secondary to solid metastases and in patients with solitary renal metastases, without spinal cord compression.

METHODS

Focused Medline and OVID database searches were conducted using relevant keywords. Only clinical articles that evaluated specific end points of interest were included in the literature review. The quality of evidence provided by each article was assessed using the ATS guidelines. The expert opinion was synthesized based on the evidence and rated as strong or weak, depending on the quality of the supporting literature.

RESULTS

Twelve surgical and 7 radiation clinical series were identified that evaluated post-treatment ambulation in patients with metastatic spinal cord compression. Only 1 surgical article met the criteria for moderate quality evidence while the remaining surgical and radiation articles presented very low quality of evidence. All articles that evaluated treatment of solitary renal metastases presented very low quality of evidence.

CONCLUSION

A strong recommendation is made for patients with high-grade cord compression due to solid tumor metastases to undergo surgical decompression with stabilization followed by radiation therapy. A weak recommendation is made for patients with solitary renal metastases without spinal cord compression to undergo spinal stereotactic radiosurgery.

Stereotactic radiosurgery for spinal metastases: case report and review of treatment options

The spine is the most common site for bone metastases. Spinal metastases can impact quality of life by causing severe pain, limitation of motion, and increased requirements for pain medication. Radiation therapy is a common form of treatment reserved for palliation of pain and for prevention or treatment of spinal cord compression. Newer approaches such as stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT) have a more precise ability to customize the radiation dose to the target tissues adjacent to critical structures, thus increasing the local control of spinal column metastases. In this report, we examine the efficacy and possible advantages of single fraction SRS using a state-of-the-art tomotherapy machine in the treatment of a patient with spinal metastases from breast cancer. We also review the literature on treatment of spinal metastases using SRS, SBRT, and other modalities.

Risk of fracture after single fraction image-guided intensity-modulated radiation therapy to spinal metastases

PURPOSE

Single-fraction image-guided intensity-modulated radiation therapy (IG-IMRT) allows for tumoricidal treatment of traditionally radioresistant cancers while sparing critical adjacent structures. Risk of vertebral fracture after IG-IMRT for spinal metastases has not been defined.

PATIENTS AND METHODS

We evaluated 62 consecutive patients undergoing single fraction IG-IMRT at 71 sites for solid organ metastases. A neuroradiologist and three spine surgeons evaluated prospectively obtained magnetic resonance/computed tomography (CT) imaging studies for post-treatment fracture development and tumor recurrence.

RESULTS

Fracture progression was noted in 27 vertebrae (39%). Multivariate logistic regression analysis showed that CT appearance, lesion location, and percent vertebral body involvement independently predicted fracture progression. Lesions located between T10 and the sacrum were 4.6 times more likely to fracture than were lesions above T10 (95% CI, 1.1 to 19.7). Lytic lesions were 6.8 times more likely to fracture than were sclerotic and mixed lesions (95% CI, 1.4 to 33.3). As percent vertebral body involvement increased, odds of fracture also increased. Patients with fracture progression had significantly higher narcotic use, change in Karnofsky performance score, and a strong trend toward higher pain scores. Local tumor progression occurred in seven patients and contributed to one fracture. Obesity, posterior element involvement, bisphosphonate use, and local kyphosis did not confer increased risk.

CONCLUSION

Vertebral fracture is common after single fraction IG-IMRT for metastatic spine lesions. Lytic disease involving more than 40% of the vertebral body and location at or below T10 confer a high risk of fracture, the presence of which yields significantly poorer clinical outcomes. These results may help clinicians identify high-risk patients who would benefit from prophylactic vertebro- or kyphoplasty.

Safety and efficacy of bevacizumab with hypofractionated stereotactic irradiation for recurrent malignant gliomas

PURPOSE

Preclinical studies suggest that inhibition of vascular endothelial growth factor (VEGF) improves glioma response to radiotherapy. Bevacizumab, a monoclonal antibody against VEGF, has shown promise in recurrent gliomas, but the safety and efficacy of concurrent bevacizumab with brain irradiation has not been extensively studied. The objectives of this study were to determine the safety and activity of this combination in malignant gliomas.

METHODS AND MATERIALS

After prior treatment with standard radiation therapy patients with recurrent glioblastoma (GBM) and anaplastic gliomas (AG) received bevacizumab (10 mg/kg intravenous) every 2 weeks of 28-day cycles until tumor progression. Patients also received 30 Gy of hypofractionated stereotactic radiotherapy (HFSRT) in five fractions after the first cycle of bevacizumab.

RESULTS

Twenty-five patients (20 GBM, 5 AG; median age 56 years; median Karnofsky Performance Status 90) received a median of seven cycles of bevacizumab. One patient did not undergo HFSRT because overlap with prior radiotherapy would exceed the safe dose allowed to the optic chiasm. Three patients discontinued treatment because of Grade 3 central nervous system intratumoral hemorrhage, wound dehiscence, and bowel perforation. Other nonhematologic and hematologic toxicities were transient. No radiation necrosis was seen in these previously irradiated patients. For the GBM cohort, overall response rate was 50%, 6-month progression-free survival was 65%; median overall survival was 12.5 months, and 1-year survival was 54%.

DISCUSSION

Bevacizumab with HFSRT is safe and well tolerated. Radiographic responses, duration of disease control, and survival suggest that this regimen is active in recurrent malignant glioma.

Influence of rotations on dose distributions in spinal stereotactic body radiotherapy (SBRT)

PURPOSE

To evaluate the impact of rotational setup errors on dose distribution in spinal stereotactic body radiotherapy (SBRT).

METHODS AND MATERIALS

Thirty-nine cone beam computed tomography (CBCT) scans from 16 SBRT treatment courses were analyzed. Alignment (including rotation) to the treatment planning computed tomography was performed, followed by translational alignment that reproduced the actual positioning. The planned fluence was then applied to determine the delivered dose to the targets and organs at risk.

RESULTS

The mean planning target volume (PTV) was 71.01 mL (SD +/- 60.05; range, 22.62-250.65 mL). Prescribed dose (to the 62-82% isodose) was 14-30 Gy in one to six fractions. The average rotational displacements were 0.38 +/- 1.21, 1.12 +/- 1.82, and -0.51 +/- 2.0 degrees with maximal rotations of -4.29, 5.76, and -6.64 degrees along the x (pitch), y (yaw), and z (roll) axes, respectively. PTV coverage changed by an average of -0.07 Gy (SD +/- 0.20 Gy) between the rotated and the original plan, representing 0.92% of prescription dose (SD +/- 2.65%). For the spinal cord, planned with 2-mm expansion to create a planning organ at risk volume (PRV), the difference in minimum dose to the upper 10% of the PRV volume was 0.03 +/- 0.3 Gy (maximum, 0.9 Gy). Other organs at risk saw insignificant changes in dose.

CONCLUSIONS

PRV expansion generally assures safe treatment delivery in the face of typically encountered rotations. Given the variability of delivered dose within this expansion for certain cases, caution should be taken to properly interpret doses to the cord when considering clinical dose limits.

Multi-institutional phase I/II trial of stereotactic body radiation therapy for liver metastases

PURPOSE

To evaluate the efficacy and tolerability of high-dose stereotactic body radiation therapy (SBRT) for the treatment of patients with one to three hepatic metastases.

PATIENTS AND METHODS

Patients with one to three hepatic lesions and maximum individual tumor diameters less than 6 cm were enrolled and treated on a multi-institutional, phase I/II clinical trial in which they received SBRT delivered in three fractions. During phase I, the total dose was safely escalated from 36 Gy to 60 Gy. The phase II dose was 60 Gy. The primary end point was local control. Lesions with at least 6 months of radiographic follow-up were considered assessable for local control. Secondary end points were toxicity and survival.

RESULTS

Forty-seven patients with 63 lesions were treated with SBRT. Among them, 69% had received at least one prior systemic therapy regimen for metastatic disease (range, 0 to 5 regimens), and 45% had extrahepatic disease at study entry. Only one patient experienced grade 3 or higher toxicity (2%). Forty-nine discrete lesions were assessable for local control. Median follow-up for assessable lesions was 16 months (range, 6 to 54 months). The median maximal tumor diameter was 2.7 cm (range, 0.4 to 5.8 cm). Local progression occurred in only three lesions at a median of 7.5 months (range, 7 to 13 months) after SBRT. Actuarial in-field local control rates at one and two years after SBRT were 95% and 92%, respectively. Among lesions with maximal diameter of 3 cm or less, 2-year local control was 100%. Median survival was 20.5 months.

CONCLUSION

This multi-institutional, phase I/II trial demonstrates that high-dose liver SBRT is safe and effective for the treatment of patients with one to three hepatic metastases.

Radiation for spinal metastatic tumors

Radiotherapeutic management of vertebral metastases varies based on the extent of disease within the spine and systemically, the histology of the tumor, and the life expectancy of the patient. The goals of pain reduction, structural stability of the axial skeleton, and maintenance of local control for the remainder of the patient's life guide the decision to proceed with a short simple course of standard therapy or a more complex approach with stereotactic regimens. The complex and rigorous processes involved in stereotactic radiotherapy for the spine require close cooperation among the radiation oncologist, neurosurgeon, orthopedic surgeon, and medical oncologist, but the clinical results show that the result is an enhanced quality of life for the patient.

Stereotactic body radiotherapy is effective salvage therapy for patients with prior radiation of spinal metastases

PURPOSE

To provide actuarial outcomes and dosimetric data for spinal/paraspinal metastases, with and without prior radiation, treated with stereotactic body radiotherapy (SBRT).

METHODS AND MATERIALS

A total of 39 consecutive patients (60 metastases) were treated with SBRT between April 2003 and August 2006 and retrospectively reviewed. In all, 23 of 60 tumors had no previous radiation (unirradiated) and 37/60 tumors had previous irradiation (reirradiated). Of 37 reirradiated tumors, 31 were treated for "salvage" given image-based tumor progression. Local failure was defined as progression by imaging and/or clinically.

RESULTS

At last follow-up, 19 patients were deceased. Median patient survival time measured was 21 months (95% CI = 8-27 months), and the 2-year survival probability was 45%. The median total dose prescribed was 24 Gy in three fractions prescribed to the 67% and 60% isodose for the unirradiated and reirradiated cohorts, respectively. The median tumor follow-up for the unirradiated and reirradiated group was 9 months (range, 1-26) and 7 months (range, 1-48) respectively. Eight of 60 tumors have progressed, and the 1- and 2-year progression-free probability (PFP) was 85% and 69%, respectively. For the salvage group the 1 year PFP was 96%. There was no significant difference in overall survival or PFP between the salvage reirradiated vs. all other tumors treated (p = 0.08 and p = 0.31, respectively). In six of eight failures the minimum distance from the tumor to the thecal sac was <or=1 mm. Of 60 tumors treated, 39 have >or=6 months follow-up and no radiation-induced myelopathy or radiculopathy has occurred.

CONCLUSION

Spine SBRT has shown preliminary efficacy and safety in patients with image-based progression of previously irradiated metastases.

Normal tissue toxicity after small field hypofractionated stereotactic body radiation

Stereotactic body radiation (SBRT) is an emerging tool in radiation oncology in which the targeting accuracy is improved via the detection and processing of a three-dimensional coordinate system that is aligned to the target. With improved targeting accuracy, SBRT allows for the minimization of normal tissue volume exposed to high radiation dose as well as the escalation of fractional dose delivery. The goal of SBRT is to minimize toxicity while maximizing tumor control. This review will discuss the basic principles of SBRT, the radiobiology of hypofractionated radiation and the outcome from published clinical trials of SBRT, with a focus on late toxicity after SBRT. While clinical data has shown SBRT to be safe in most circumstances, more data is needed to refine the ideal dose-volume metrics.