Stereotactic radiosurgery for the definitive, noninvasive treatment of brain metastases

Current Status of Hybrid PET/MRI in Oncologic Imaging

OBJECTIVE

This review article explores recent advancements in PET/MRI for clinical oncologic imaging.

CONCLUSION

Radiologists should understand the technical considerations that have made PET/MRI feasible within clinical workflows, the role of PET tracers for imaging various molecular targets in oncology, and advantages of hybrid PET/MRI compared with PET/CT. To facilitate this understanding, we discuss clinical examples (including gliomas, breast cancer, bone metastases, prostate cancer, bladder cancer, gynecologic malignancy, and lymphoma) as well as future directions, challenges, and areas for continued technical optimization for PET/MRI.

A model evaluation study for treatment planning of laser-induced thermal therapy

A cross-validation analysis evaluating computer model prediction accuracy for a priori planning magnetic resonance-guided laser-induced thermal therapy (MRgLITT) procedures in treating focal diseased brain tissue is presented. Two mathematical models are considered. (1) A spectral element discretisation of the transient Pennes bioheat transfer equation is implemented to predict the laser-induced heating in perfused tissue. (2) A closed-form algorithm for predicting the steady-state heat transfer from a linear superposition of analytic point source heating functions is also considered. Prediction accuracy is retrospectively evaluated via leave-one-out cross-validation (LOOCV). Modelling predictions are quantitatively evaluated in terms of a Dice similarity coefficient (DSC) between the simulated thermal dose and thermal dose information contained within N = 22 MR thermometry datasets. During LOOCV analysis, the transient model's DSC mean and median are 0.7323 and 0.8001 respectively, with 15 of 22 DSC values exceeding the success criterion of DSC ≥ 0.7. The steady-state model's DSC mean and median are 0.6431 and 0.6770 respectively, with 10 of 22 passing. A one-sample, one-sided Wilcoxon signed-rank test indicates that the transient finite element method model achieves the prediction success criteria, DSC ≥ 0.7, at a statistically significant level.

Time-delayed contrast-enhanced MRI improves detection of brain metastases and apparent treatment volumes

OBJECTIVE

Contrast-enhanced MRI is the preeminent diagnostic test for brain metastasis (BM). Detection of BMs for stereotactic radiosurgery (SRS) planning may improve with a time delay following administration of a high-relaxivity agent for 1.5-T and 3-T imaging systems. Metastasis detection with time-delayed MRI was evaluated in this study.

METHODS

Fifty-three volumetric MRI studies from 38 patients undergoing SRS for BMs were evaluated. All studies used 0.1-mmol/kg gadobenate dimeglumine (MultiHance; Bracco Diagnostics) immediately after injection, followed by 2 more axial T1-weighted sequences after 5-minute intervals (final image acquisition commenced 15 minutes after contrast injection). Two studies were motion limited and excluded. Two hundred eighty-seven BMs were identified. The studies were randomized and examined separately by 3 radiologists, who were blinded to the temporal sequence. Each radiologist recorded the number of BMs detected per scan. A Wilcoxon signed-rank test compared BM numbers between scans. One radiologist determined the scan on which BMs were best defined. All confirmed, visible tumors were contoured using iPlan RT treatment planning software on each of the 3 MRI data sets. A linear mixed model was used to analyze volume changes.

RESULTS

The interclass correlations for Scans 1, 2, and 3 were 0.7392, 0.7951, and 0.7290, respectively, demonstrating excellent interrater reliability. At least 1 new lesion was detected in the second scan as compared with the first in 35.3% of subjects (95% CI 22.4%-49.9%). The increase in BM numbers between Scans 1 and 2 ranged from 1 to 10. At least 1 new lesion was detected in the third scan as compared with the second in 21.6% of subjects (95% CI 11.3%-35.3%). The increase in BM numbers between Scans 2 and 3 ranged from 1 to 9. Between Scans 1 and 3, additional tumors were seen on 43.1% of scans (increase ranged from 1 to 14). The median increase in tumor number for all comparisons was 1. There was a significant increase in number of BMs detected from Scan 1 to Scan 2 (p < 0.0367) and from Scan 1 to Scan 3 (p < 0.0264). In 34 of the 51 subjects (66.7%), the radiologist selected the third scan as the one providing the clearest tumor definition. There was an average 25.4% increase in BM volume between Scans 1 and 2 (p < 0.0001) and a 9% increase in BM volume between Scans 2 and 3 (p = 0.0001).

CONCLUSIONS

In patients who are being prepared for SRS of BMs, delayed MRI after contrast injection revealed more targets that needed treatment. In addition, apparent treatment volumes increased with a time delay. To avoid missing tumors that could be treated at the time of planned SRS and resultant "treatment failures," the authors recommend that postcontrast MR images be acquired between 10 and 15 minutes after injection in patients undergoing SRS for treatment of BMs.

Characteristics and treatments of large cystic brain metastasis: radiosurgery and stereotactic aspiration

Brain metastasis represents one of the most common causes of intracranial tumors in adults, and the incidence of brain metastasis continues to rise due to the increasing survival of cancer patients. Yet, the development of cystic brain metastasis remains a relatively rare occurrence. In this review, we describe the characteristics of cystic brain metastasis and evaluate the combined use of stereotactic aspiration and radiosurgery in treating large cystic brain metastasis. The results of several studies show that stereotactic radiosurgery produces comparable local tumor control and survival rates as other surgery protocols. When the size of the tumor interferes with radiosurgery, stereotactic aspiration of the metastasis should be considered to reduce the target volume as well as decreasing the chance of radiation induced necrosis and providing symptomatic relief from mass effect. The combined use of stereotactic aspiration and radiosurgery has strong implications in improving patient outcomes.

Bevacizumab might potentiate the chemotherapeutic effect in breast cancer patients with leptomeningeal carcinomatosis

BACKGROUND/PURPOSE

Patients with leptomeningeal carcinomatosis (LC) from breast cancer is generally resistant to systemic chemotherapy. Bevacizumab may increase intratumor concentration of the chemotherapeutic agents through vascular normalization, although the overall clinical benefit of bevacizumab for metastatic breast cancer is under debate.

METHODS

Successful treatment of two breast cancer patients who developed LC after whole brain irradiation treatment for the brain metastases is reported here. Both patients have refractory disease to taxane and anthracycline, and both of them have disease progression under intrathecal methotrexate treatment for LC.

RESULTS

The two patients received systemic chemotherapy with bevacizumab (7.5 mg/kg infusion on Day 1), cisplatin (80 mg/m(2) infusion for 24 hours on Day 2), and etoposide (80 mg/m(2) infusion for 2 hours on Days 2-4) at 21-28 day intervals. Both patients achieved best response of negative cerebral spinal fluid cytology study and dramatic improvement of neurologic deficit after treatment. Their overall survival after development of LC was 8 months and 7.5 months respectively.

CONCLUSION

Bevacizumab plus etoposide and cisplatin might be a new option for breast cancer patients with LC. Further prospective study is warranted.

Hypofractionated radiosurgery has a better safety profile than single fraction radiosurgery for large resected brain metastases

The purpose of this study is to compare the safety and efficacy of single fraction radiosurgery (SFR) with hypofractionated radiosurgery (HR) for the adjuvant treatment of large, surgically resected brain metastases. Seventy-five patients with 76 resection cavities ≥ 3 cm received 15 Gray (Gy) × 1 SFR (n = 40) or 5-8 Gy × 3-5 HR (n = 36). Cumulative incidence of local failure (LF) and radiation necrosis (RN) was estimated accounting for death as a competing risk and compared with Gray's test. The effect of multiple covariates was evaluated with the Fine-Gray proportional hazards model. The most common HR dose-fractionation schedules were 6 Gy × 5 (44%), 7-8 Gy × 3 (36%), and 6 Gy × 4 (8%). The median follow-up was 11 months (range 2-71). HR patients had larger median resection cavity volumes (24.0 vs. 13.3 cc, p < 0.001), planning target volumes (PTV) (37.7 vs. 20.5 cc, p < 0.001), and cavity to PTV expansion margins (2 vs. 1.5 mm, p = 0.002) than SFR patients. Cumulative incidence of LF (95% CI) at 6 and 12-months for HR versus SFR was 18.9% (0.07-0.34) versus 15.9% (0.06-0.29), and 25.6% (0.12-0.42) versus 27.2% (0.14-0.42), p = 0.80. Cumulative incidence of RN (95% CI) at 6 and 12 months for HR vs. SFR was 3.3% (0.00-0.15) versus 10.7% (0.03-0.23), and 10.3% (0.02-0.25) versus 19.2% (0.08-0.34), p = 0.28. On multivariable analysis, SFR was significantly associated with an increased risk of RN, with a HR of 3.81 (95% CI 1.04-13.93, p = 0.043). Hypofractionated radiosurgery may be the more favorable treatment approach for radiosurgery of cavities 3-4 cm in size and greater.

Quantifying isocenter measurements to establish clinically meaningful thresholds

A dataset range of isocenter congruency verification tests have been examined from a statistical perspective for the purpose of establishing tolerance levels that are meaningful, based on the fundamental limitation of linear accelerator isocentricity and the demands of a high-precision stereotactic radiosurgery program. Using a laser-defined isocenter, a total of 149 individual isocenter congruency tests were examined with recorded values for ideal spatial corrections to the isocenter test tool. These spatial corrections were determined from radiation exposures recorded on an electronic portal imaging device (EPID) at various gantry, collimator, and treatment couch combinations. The limitations of establishing an ideal isocenter were quantified from each variable which contributed to uncertainty in isocenter definition. Individual contributors to uncertainty, specifically, daily positioning setup errors, gantry sag, multileaf collimator (MLC) offset, and couch walkout, were isolated from isocenter congruency measurements to determine a clinically meaningful isocenter measurement. Variations in positioning of the test tool constituted, on average, 0.38 mm magnitude of correction. Gantry sag and MLC offset contributed 0.4 and 0.16 mm, respectively. Couch walkout had an average degrading effect to isocenter of 0.72 mm. Considering the magnitude of uncertainty contributed by each uncertainty variable and the nature of their combination, an appropriate schedule action and immediate action level were determined for use in analyzing daily isocenter congruency test results in a stereotactic radiosurgery (SRS) program. The recommendations of this study for this linear accelerator include a schedule action level of 1.25 mm and an immediate action level of 1.50mm, requiring prompt correction response from clinical medical physicists before SRS or stereotactic body radiosurgery (SBRT) is administered. These absolute values were derived from considering relative data from a specific linear accelerator and, therefore, represent a means by which a numerical quantity can be used as a test threshold with relative specificity to a particular linear accelerator.

A nomogram to predict brain metastasis as the first relapse in curatively resected non-small cell lung cancer patients

OBJECTIVES

Development of brain metastasis results in a significant reduction in overall survival. However, there is no an effective tool to predict brain metastasis in non-small cell lung cancer (NSCLC) patients. We conducted this study to develop a feasible nomogram that can predict metastasis to the brain as the first relapse site in patients with curatively resected NSCLC.

MATERIAL AND METHODS

A retrospective review of NSCLC patients who had received curative surgery at National Cancer Center (Goyang, South Korea) between 2001 and 2008 was performed. We chose metastasis to the brain as the first relapse site after curative surgery as the primary endpoint of the study. A nomogram was modeled using logistic regression.

RESULTS

Among 1218 patients, brain metastasis as the first relapse developed in 87 patients (7.14%) during the median follow-up of 43.6 months. Occurrence rates of brain metastasis were higher in patients with adenocarcinoma or those with a high pT and pN stage. Younger age appeared to be associated with brain metastasis, but this result was not statistically significant. The final prediction model included histology, smoking status, pT stage, and the interaction between adenocarcinoma and pN stage. The model showed fairly good discriminatory ability with a C-statistic of 69.3% and 69.8% for predicting brain metastasis within 2 years and 5 years, respectively. Internal validation using 2000 bootstrap samples resulted in C-statistics of 67.0% and 67.4% which still indicated good discriminatory performances.

CONCLUSION

The nomogram presented here provides the individual risk estimate of developing metastasis to the brain as the first relapse site in patients with NSCLC who have undergone curative surgery. Surveillance programs or preventive treatment strategies for brain metastasis could be established based on this nomogram.

Efficacy of surgical treatment for brain metastasis in patients with non-small cell lung cancer

PURPOSE

Patients with non-small cell lung cancer (NSCLC) and simultaneously having brain metastases at the initial diagnosis, presenting symptoms related brain metastasis, survived shorter duration and showed poor quality of life. We analyzed our experiences on surgical treatment of brain metastasis in patients with NSCLC.

MATERIALS AND METHODS

We performed a single-center, retrospective review of 36 patients with NSCLC and synchronous brain metastases between April 2006 and December 2011. Patients were categorized according to the presence of neurological symptoms and having a brain surgery. As a result, 14 patients did not show neurological symptoms and 22 patients presented neurological symptoms. Symptomatic 22 patients were divided into two groups according to undergoing brain surgery (neurosurgery group; n=11, non-neurosurgery group; n=11). We analyzed overall surgery (OS), intracranial progression-free survival (PFS), and quality of life.

RESULTS

Survival analysis showed there was no difference between patients with neurosurgery (OS, 12.1 months) and non-neurosurgery (OS, 10.2 months; p=0.550). Likewise for intracranial PFS, there was no significant difference between patients with neurosurgery (PFS, 6.3 months) and non-neurosurgery (PFS, 5.3 months; p=0.666). Reliable neurological one month follow up by the Medical Research Council neurological function evaluation scale were performed in symptomatic 22 patients. The scale improved in eight (73%) patients in the neurosurgery group, but only in three (27%) patients in the non-neurosurgery group (p=0.0495).

CONCLUSION

Patients with NSCLC and synchronous brain metastases, presenting neurological symptoms showed no survival benefit from neurosurgical resection, although quality of life was improved due to early control of neurological symptoms.

Survival and prognostic factors in patients treated with stereotactic radiotherapy for brain metastases

BACKGROUND

Stereotactic radiation therapy (SRT) of brain metastases is used with good effect around the world, but no consensus exists regarding which prognostic factors that are related to favourable or unfavourable prognosis after the treatment. A better definition of these factors will ensure a more precise application of the treatment.

MATERIAL AND METHODS

A consecutive cohort of the 198 patients treated for brain metastases with SRT without concurrent whole-brain radiation therapy at our department from 2001 to 2012 was retrospectively analysed.

RESULTS

Median survival was seven months and median time to clinical cerebral progression was eight months. The multivariate analysis revealed age ≥ 65 years, Performance Status ≥ 2, extracranial metastases and size of metastasis > 20 mm as independent prognostic factors related to shorter survival. No factors were independently related to clinical cerebral progression.

CONCLUSION

We identified four prognostic factors related to survival after SRT for brain metastases. The grouping of patients by these factors is useful to determine the level of treatment. We discourage the delivery of SRT to patients with 3-4 unfavourable prognostic factors because of the very short median survival of two months.

Platinum sensitivity and CD133 expression as risk and prognostic predictors of central nervous system metastases in patients with epithelial ovarian cancer

Background

To characterize prognostic and risk factors of central nervous system (CNS) metastases in patients with epithelial ovarian cancer (EOC).

Methods

A retrospective analysis of Xijing Hospital electronic medical records was conducted to identify patients with pathologically confirmed EOC and CNS metastases. In addition to patient demographics, tumor pathology, treatment regimens, and clinical outcomes, we compared putative cancer stem cell marker CD133 expression patterns in primary and metastatic lesions as well as in recurrent EOC with and without CNS metastases.

Results

Among 1366 patients with EOC, metastatic CNS lesions were present in 29 (2.1%) cases. CD133 expression in primary tumor was the only independent risk factor for CNS metastases; whilst the extent of surgical resection of primary EOC and platinum resistance were two independent factors significantly associated with time to CNS metastases. Absence of CD133 expression in primary tumors was significantly associated with high platinum sensitivity in both patient groups with and without CNS metastases. Platinum resistance and CD133 cluster formation in CNS metastases were associated with decreased survival, while multimodal therapy including stereotactic radiosurgery (SRS) for CNS metastases was associated with increased survival following the diagnosis of CNS metastases.

Conclusions

These data suggest that there exist a positive association between CD133 expression in primary EOC, platinum resistance and the increased risk of CNS metastases, as well as a less favorable prognosis of EOC. The absence of CD133 clusters and use of multimodal therapy including SRS could improve the outcome of metastatic lesions. Further investigation is warranted to elucidate the true nature of the association between platinum sensitivity, CD133 expression, and the risk and prognosis of CNS metastases from EOC.

Brain metastases in breast cancer

Brain metastases are less common than bone or visceral metastases in patients with breast cancer. The overall prognosis of breast cancer patients with brain metastases remains poor, and these metastases are less responsive to systemic therapies. Brain metastasis is associated with a reduced quality of life due to progressive neurologic impairments. Recently, a trend of increased incidence of brain metastases in breast cancer has been noted. Reasons for this increased incidence include the more frequent use of sensitive detection methods such as contrast-enhanced magnetic resonance imaging and increased awareness of brain metastasis among patients and clinicians. Adjuvant and systemic therapy with drugs that have a low blood-brain barrier penetrance can lead to an increased risk of brain metastases in breast cancer patients. Molecular subtype is a predictive factor for overall survival after developing brain metastases. Patients who do not have a poor prognosis based on previously identified prognostic factors should be treated with radiation therapy to control symptoms. Whole-brain radiation therapy, stereotactic irradiation and surgery are tools for the local treatment of brain metastases. Novel molecular target therapy, including HER2-targeted therapy, has demonstrated an antitumor effect on brain metastases. In this review, we provide a practical algorithm for the treatment of breast cancer brain metastases. This review provides an overview of the incidence, risk factors, diagnosis, prognostic factors and current and potential future management strategies of breast cancer brain metastases.

Treatment outcomes and prognostic factors for patients with brain metastases from breast cancer of each subtype: a multicenter retrospective analysis

To define prognostic factors for breast cancer patients with brain metastases, compare their clinical courses and prognoses according to breast cancer subtypes, and analyze the causes of death in such patients. We retrospectively analyzed 1,466 patients diagnosed with brain metastases between April 1, 2001 and December 31, 2012, from 24 institutions of the Japan Clinical Oncology Group. Overall, 1,256 patients with brain metastases were included. The median overall survival (OS) was 8.7 months (95 % confidence interval [CI] 7.8-9.6 months). Univariate and multivariate analyses revealed that patients diagnosed with brain metastasis within 6 months of metastatic breast cancer diagnoses, asymptomatic brain disease, or HER2-positive/estrogen receptor-positive tumors had increased OS. Median OS after the development of brain metastases was 9.3 months (95 % CI 7.2-11.3) for the luminal type, 16.5 months (95 % CI 11.9-21.1) for the luminal-HER2 type, 11.5 months (95 % CI 9.1-13.8) for the HER2 type, and 4.9 months (95 % CI 3.9-5.9) for the triple-negative type. Luminal-HER2 type patients had significantly longer OS than patients with the luminal type (hazard ratio [HR] = 1.50, P < 0.0001) and triple-negative type (HR = 1.97, P < 0.0001); no significant differences were noted compared to HER2-type patients (HR = 1.19, P = 0.117). The prognosis and clinical course of patients with brain metastasis from breast cancer before and after developing brain metastases vary according to subtype. Focusing on the subtypes of breast cancer can optimize the prevention, early detection, and improved treatment of brain metastases.

Predictors of individual tumor local control after stereotactic radiosurgery for non-small cell lung cancer brain metastases

PURPOSE

To evaluate local control rates and predictors of individual tumor local control for brain metastases from non-small cell lung cancer (NSCLC) treated with stereotactic radiosurgery (SRS).

METHODS AND MATERIALS

Between June 1998 and May 2011, 401 brain metastases in 228 patients were treated with Gamma Knife single-fraction SRS. Local failure was defined as an increase in lesion size after SRS. Local control was estimated using the Kaplan-Meier method. The Cox proportional hazards model was used for univariate and multivariate analysis. Receiver operating characteristic analysis was used to identify an optimal cutpoint for conformality index relative to local control. A P value <.05 was considered statistically significant.

RESULTS

Median age was 60 years (range, 27-84 years). There were 66 cerebellar metastases (16%) and 335 supratentorial metastases (84%). The median prescription dose was 20 Gy (range, 14-24 Gy). Median overall survival from time of SRS was 12.1 months. The estimated local control at 12 months was 74%. On multivariate analysis, cerebellar location (hazard ratio [HR] 1.94, P=.009), larger tumor volume (HR 1.09, P<.001), and lower conformality (HR 0.700, P=.044) were significant independent predictors of local failure. Conformality index cutpoints of 1.4-1.9 were predictive of local control, whereas a cutpoint of 1.75 was the most predictive (P=.001). The adjusted Kaplan-Meier 1-year local control for conformality index ≥ 1.75 was 84% versus 69% for conformality index <1.75, controlling for tumor volume and location. The 1-year adjusted local control for cerebellar lesions was 60%, compared with 77% for supratentorial lesions, controlling for tumor volume and conformality index.

CONCLUSIONS

Cerebellar tumor location, lower conformality index, and larger tumor volume were significant independent predictors of local failure after SRS for brain metastases from NSCLC. These results warrant further investigation in a prospective setting.

Stereotactic radiosurgery (SRS) for brain metastases: a systematic review

In many patients with brain metastases, the primary therapeutic aim is symptom palliation and maintenance of neurologic function, but in a subgroup, long-term survival is possible. Local control in the brain, and absent or controlled extracranial sites of disease are prerequisites for favorable survival. Stereotactic radiosurgery (SRS) is a focal, highly precise treatment option with a long track record. Its clinical development and implementation by several pioneering institutions eventually rendered possible cooperative group randomized trials. A systematic review of those studies and other landmark studies was undertaken. Most clinicians are aware of the potential benefits of SRS such as a short treatment time, a high probability of treated-lesion control and, when adhering to typical dose/volume recommendations, a low normal tissue complication probability. However, SRS as sole first-line treatment carries a risk of failure in non-treated brain regions, which has resulted in controversy around when to add whole-brain radiotherapy (WBRT). SRS might also be prescribed as salvage treatment in patients relapsing despite previous SRS and/or WBRT. An optimal balance between intracranial control and side effects requires continued research efforts.

Evaluation of results of linac-based radiosurgery for brain metastases from primary lung cancer

AIM

The purpose of our review was to evaluate results of radiosurgery for patients with brain metastases from lung cancer.

BACKGROUND

Lung cancer is the leading cause of death from cancer and the most common source of brain metastases. Radiosurgery allows the precise focal delivery of a high single radiation dose to brain metastases and results in high rates of local control.

MATERIALS AND METHODS

83 patients were treated between 2006 and 2008. We evaluated local control and outcome after radiosurgery and identified prognostic factors.

RESULTS

Median survival in the whole group was 7.8 months from radiosurgery and 11 months from diagnosis. Median survival in classes I, II and III was 13.2, 8.2 and 2.2 months. For 94% of patients symptoms improved or stabilised at the first follow-up visit and this status did not change during 7.1 months. According to the univariate analysis, factors associated with improved survival included: RPA class 1 compared with RPA 2 and 3, RPA class 2 compared with RPA 3, KPS > 70, control of the primary disease, radiosurgery performed more than once, level of haemoglobin >7 mmol/1, absence of extracranial metastases, volume of the biggest lesion <11 cm(3). The multivariate analysis confirmed a significant influence on survival for the following factors: RPA class 1 as compared with RPA 3, KPS > 70, absence of extracranial metastases, multiplicity of radiosurgery.

CONCLUSIONS

Stereotactic radiosurgery is a safe and effective treatment. It proved to be effective and safe in older patients. Selection of patients who are likely to benefit most should be based on prognostic factors. KPS proved to be the most important prognostic factor. In the RPA III group (patients with KPS < 70) survival time was similar to that achieved after symptomatic medical management.

Predicting the development of brain metastases in patients with local/regional melanoma

BACKGROUND

The brain is a common site of recurrence in melanoma patients. Brain recurrence may present as a seizure, hemorrhage, or death. We sought to determine predictors of brain metastases in patients with primary and regional melanoma in order to facilitate targeted screening.

METHODS

Prospectively maintained databases were used to identify patients treated for local or regional melanoma who developed stage IV melanoma with and without brain metastasis at initial recurrence. One hundred twenty patients were identified with brain relapse and compared to 487 patients without brain recurrence.

RESULTS

On univariate analysis, patients with brain metastases were younger (55 vs. 59yrs, P = 0.04) but did not differ in primary site (head and neck 23% vs. 21%, P = 0.20). Brain metastasis patients had thinner primaries (mean 3.4 vs. 4.5 mm, P = 0.01). There were no other pathologic differences including ulceration (55% vs. 53%, P = 0.75), mitoses (7 vs.7.5, P = 0.61) or histologic subtype. Younger age and decreased Breslow thickness were independently associated with brain metastases at stage IV recurrence (OR = 1.10 P = 0.01 and OR = 1.02 P = 0.02, respectively).

CONCLUSIONS

Our analysis, the largest to date, demonstrates that thinner Breslow depth and younger age were associated with brain recurrence at first presentation with Stage IV disease.

Stereotactic radiosurgery for treatment of brain metastases. A report of the DEGRO Working Group on Stereotactic Radiotherapy

BACKGROUND

This report from the Working Group on Stereotaktische Radiotherapie of the German Society of Radiation Oncology (Deutsche Gesellschaft für Radioonkologie, DEGRO) provides recommendations for the use of stereotactic radiosurgery (SRS) on patients with brain metastases. It considers existing international guidelines and details them where appropriate.

RESULTS AND DISCUSSION

The main recommendations are: Patients with solid tumors except germ cell tumors and small-cell lung cancer with a life expectancy of more than 3 months suffering from a single brain metastasis of less than 3 cm in diameter should be considered for SRS. Especially when metastases are not amenable to surgery, are located in the brain stem, and have no mass effect, SRS should be offered to the patient. For multiple (two to four) metastases--all less than 2.5 cm in diameter--in patients with a life expectancy of more than 3 months, SRS should be used rather than whole-brain radiotherapy (WBRT). Adjuvant WBRT after SRS for both single and multiple (two to four) metastases increases local control and reduces the frequency of distant brain metastases, but does not prolong survival when compared with SRS and salvage treatment. As WBRT carries the risk of inducing neurocognitive damage, it seems reasonable to withhold WBRT for as long as possible.

CONCLUSION

A single (marginal) dose of 20 Gy is a reasonable choice that balances the effect on the treated lesion (local control, partial remission) against the risk of late side effects (radionecrosis). Higher doses (22-25 Gy) may be used for smaller (< 1 cm) lesions, while a dose reduction to 18 Gy may be necessary for lesions greater than 2.5-3 cm. As the infiltration zone of the brain metastases is usually small, the GTV-CTV (gross tumor volume-clinical target volume) margin should be in the range of 0-1 mm. The CTV-PTV (planning target volume) margin depends on the treatment technique and should lie in the range of 0-2 mm. Distant brain recurrences fulfilling the aforementioned criteria can be treated with SRS irrespective of previous WBRT.

A Prospective Phase II Trial of Fractionated Stereotactic Intensity Modulated Radiotherapy With or Without Surgery in the Treatment of Patients With 1 to 3 Newly Diagnosed Symptomatic Brain Metastases

BACKGROUND:

Several studies have demonstrated that omitting the routine use of adjuvant whole-brain radiation therapy for patients with newly diagnosed brain metastases may be a reasonable first-line strategy. Retrospective evidence suggests that fractionated stereotactic radiotherapy (fSRT) may have a lower level of toxicity with equivalent efficacy in comparison with radiosurgery.

OBJECTIVE:

To study the phase II efficacy of using a focally directed treatment strategy for symptomatic brain metastases by the use of fSRT with or without surgery and omitting the routine use of adjuvant whole-brain radiation therapy.

METHODS:

We used a Fleming single-stage design of 40 patients. Patients were eligible if they presented with 1 to 3 newly diagnosed symptomatic brain metastases, Karnofsky performance scale (KPS) greater than 60, and histological confirmation of primary disease. Patients underwent fSRT with the use of a dose of 30 Gy in 5 intensity-modulated fractions as primary or adjuvant treatment after surgical resection. The primary end point was the proportion of patients who experienced neurological death. Secondary end points were overall survival, time to KPS &lt;70, and progression-free survival.

RESULTS:

Of 40 patients accrued, 39 were eligible for analysis. The proportion of patients dying of neurological causes was 13% (5 patients), which includes 3 patients with an unknown cause of death. Median overall survival, time to KPS &lt;70, and progression-free survival were 16 (95% confidence interval, 9-23), 14 (95% confidence interval, 7-20), and 11 (95% confidence interval, 4-21) months, respectively.

CONCLUSION:

A focally directed treatment strategy using fSRT with or without surgery appears to be an effective initial strategy. Based on the results of this phase II clinical trial, further study is warranted.

Cyberknife stereotactic radiosurgery for the re-irradiation of brain lesions: a single-centre experience

PURPOSE

The aim of our study was to retrospectively evaluate the feasibility and clinical benefit of cyberknife stereotactic radiosurgery (CSRS) in patients treated at Florence University for recurrent, pre-irradiated brain lesions.

MATERIALS AND METHODS

Thirteen patients were retreated with cyberknife. Mean age was 47.1 years (range 33-77 years). Karnofsky performance status ranged from 60 to 100 (median 80). Eleven (84.6%) out of 13 patients had metastatic lesions: four (36.4%) had primary lung, three (27.2%) had primary breast cancer and four (36.4%) other types of solid malignancies. Two (15.4%) out of 13 patients had recurrent of glioblastoma.

RESULTS

In terms of compliance with CSRS, the majority of patients did not develop any acute side effects. However, two (15.4%) out of 13 patients developed acute grade 2 toxicity requiring an increase of steroid medication. At the time of the last follow-up, response rates were as follows: complete response in one case (16.6%), partial response in three (50%) and stable disease in two (33.4%).

CONCLUSIONS

Re-irradiation with CSRS is a feasible and effective option for pre-irradiated, recurrent brain lesions to obtain clinical benefit without excessive acute toxicity.

Radiologic and histologic consequences of radiosurgery for brain tumors

Progressively enlarging encephalopathic changes are now well-documented effects of gamma knife radiosurgery (GKRS) occurring ~3-30 months after treatment of both benign and malignant brain lesions. These changes can be variably associated with inflammatory demyelination and necrosis and/or recurrent tumor. While radiographic differentiation between encephalopathic changes and recurrent tumor is of high clinical relevance, confident interpretation of post-radiosurgery imaging changes can be challenging or even impossible in some cases. Gadolinium-enhanced MRI of these lesions reveals variable amounts of enhancing and non-enhancing components within these lesions that have not been clearly correlated with structural-pathologic change. The goal of this study is to characterize the histopathological changes associated with enhancing versus non-enhancing regions of GKRS-treated lesions. MRI images of patients with progressive, etiologically ambiguous brain lesions following GKRS were reviewed prior to explorative neurosurgery. Chosen for this study were lesions in which distinct areas of enhancement and non-enhancement of at least 5 mm in size could be identified (n = 16). Distinctly enhancing and non-enhancing areas were separately biopsied and histologically evaluated. Only cases with uniform histological results are presented in this study. Enhancing and non-enhancing areas in post GKRS lesions represent separate pathological changes. Radiographically enhancing areas correlate either with recurrent tumor growth or inflammatory demyelinating changes. Lack of radiographic enhancement correlates with coagulative necrosis if the sample is taken from the center of the lesion, or with reactive astrocytosis if the sample is taken from the periphery. Separate biopsy of enhancing and non-enhancing regions of post-GKRS encephalopathy was able to confirm that the pathologies in these areas are distinct. These findings allow for better-informed correlation of histological and radiological changes and a better understanding of post-treatment tissue pathology.

Radiosurgery in the treatment of malignant brain tumors

Brain metastases are an attractive target for radiosurgery. Over a period of 6 years, 400 patients with brain metastases have been treated with radiosurgery. Of these patients, 61% had solitary brain metastases and 39% had multiple brain metastases. Local control was achieved in 90% and improvement of severe neurological symptoms in 76%. The median survival time was 8 months. The significant prognostic factors for survival in patients with solitary brain metastases were age, Karnofsky performance status, severity of symptoms, extent of progressive malignant disease outside the brain, histology, interval between diagnosis of primary tumor and brain metastasis, and minimum applied dosage. The significant prognostic factors in patients with multiple brain metastases were sex, Karnofsky performance status and presence of progressive disease outside the brain.

The impact of radiosurgery fractionation and tumor radiobiology on the local control of brain metastases

Object

Experience with whole-brain radiation therapy for metastatic tumors in the brain has identified a subset of tumors that exhibit decreased local control with fractionated regimens and are thus termed radioresistant. With the advent of frameless radiosurgery, fractionated radiosurgery (2–5 fractions) is being used increasingly for metastatic tumors deemed too large or too close to crucial structures to be treated in a single session. The authors retrospectively reviewed metastatic brain tumors treated at 2 centers to analyze the dependency of local control rates on tumor radiobiology and dose fractionation.

Methods

The medical records of 214 patients from 2 institutions with radiation-naive metastatic tumors in the brain treated with radiosurgery given either as a single dose or in 2–5 fractions were analyzed retrospectively. The authors compared the local control rates of the radiosensitive with the radioresistant tumors after either single-fraction or fractionated radiosurgery.

Results

There was no difference in local tumor control rates in patients receiving single-fraction radiosurgery between radioresistant and radiosensitive tumors (p = 0.69). However, after fractionated radiosurgery, treatment for radioresistant tumors failed at a higher rate than for radiosensitive tumors with an OR of 5.37 (95% CI 3.83–6.91, p = 0.032).

Conclusions

Single-fraction radiosurgery is equally effective in the treatment of radioresistant and radiosensitive metastatic tumors in the brain. However, fractionated stereotactic radiosurgery is less effective in radioresistant tumor subtypes. The authors recommend that radioresistant tumors be treated in a single fraction when possible and techniques for facilitating single-fraction treatment or dose escalation be considered for larger radioresistant lesions.

Isolated cerebral metastasis of a triceps muscle leiomyosarcoma: a case report

Leiomyosarcomas are rare malignant neoplasms. Intracranial metastases of this tumour are even less frequently observed and have mostly been described from uterine leiomyosarcomas. In this article, we describe the case of a single right frontal subcortical cerebral metastasis in a patient with a right triceps muscle leiomyosarcoma. A right-sided frontal craniotomy with macroscopically complete tumour removal was performed, followed by combined radio-chemotherapy. The patient died 10 months after the initial diagnosis of the intracranial metastasis due to systemic tumour progression, without any evidence of intracranial recurrence.

The prognostic value of tumor necrosis in patients undergoing stereotactic radiosurgery of brain metastases

Background

This retrospective study investigated the outcome of patients with brain metastases after radiosurgery with special emphasis on prognostic impact of visible intratumoral necrosis on survival and local control.

Methods

From 1998 through 2008, 149 patients with brain metastases from solid tumors were treated with stereotactic radiotherapy at Luebeck University. Median age was 58.4 years with 11%, 78%, 10% in recursive partitioning analysis (RPA) classes I, II, III, respectively. 70% had 1 metastasis, 29% 2-3 metastases, 2 patients more than 3 metastases, 71% active extracranial disease. Median volume of metastatic lesions was 4.7 cm³, median radiosurgery dose 22 Gy (single fraction). 71% of patients received additional whole-brain irradiation (WBI). All patients were analyzed regarding survival, local, distant failure and prognostic factors, side effects and changes in neurologic symptoms after radiotherapy. The type of contrast-enhancement in MR imaging was also analyzed; metastatic lesions were classified as containing necrosis if they appeared as ring-enhancing with central areas of no or minimal contrast enhancement.

Results

Median survival was 7.0 months with 1-year and 5-year survival rates of 33% and 0.4%, respectively. Tumor necrosis (ring-enhancement) was visible on pretreatment MRI scans in 56% of all lesions and lesions with necrosis were larger than non-necrotic lesions (6.7 cm³ vs. 3.2 cm³, p = 0.01). Patients with tumor necrosis had a median survival of 5.4 months, patients without tumor necrosis 7.2 months. Local control rate in the irradiated volume was 70%, median survival without local failure 17.8 months. Control in the brain outside the irradiated volume was 60%, median survival without distant failure 14.0 months. Significant prognostic factors for overall survival were KPS (p = 0.001), presence of tumor necrosis on pretreatment MRI (p = 0.001) with RPA-class and WBI reaching marginal significance (each p = 0.05). Prognostic impact of tumor necrosis remained significant if only smaller tumors with a volume below 3.5 cm³ (p = 0.03). Side effects were rare, only one patient suffered from serious acute side effects.

Conclusions

Results of this retrospective study support that stereotactic radiotherapy is an effective treatment option for patients with metastatic brain lesions. The prognostic impact of visible tumor necrosis (ring-enhancement) on pretreatment MRI scans should be further investigated.

Hypofractionated radiosurgery for intact or resected brain metastases: defining the optimal dose and fractionation

Background

Hypofractionated Radiosurgery (HR) is a therapeutic option for delivering partial brain radiotherapy (RT) to large brain metastases or resection cavities otherwise not amenable to single fraction radiosurgery (SRS). The use, safety and efficacy of HR for brain metastases is not well characterized and the optimal RT dose-fractionation schedule is undefined.

Methods

Forty-two patients treated with HR in 3-5 fractions for 20 (48%) intact and 22 (52%) resected brain metastases with a median maximum dimension of 3.9 cm (0.8-6.4 cm) between May 2008 and August 2011 were reviewed. Twenty-two patients (52%) had received prior radiation therapy. Local (LC), intracranial progression free survival (PFS) and overall survival (OS) are reported and analyzed for relationship to multiple RT variables through Cox-regression analysis.

Results

The most common dose-fractionation schedules were 21 Gy in 3 fractions (67%), 24 Gy in 4 fractions (14%) and 30 Gy in 5 fractions (12%). After a median follow-up time of 15 months (range 2-41), local failure occurred in 13 patients (29%) and was a first site of failure in 6 patients (14%). Kaplan-Meier estimates of 1 year LC, intracranial PFS, and OS are: 61% (95% CI 0.53 – 0.70), 55% (95% CI 0.47 – 0.63), and 73% (95% CI 0.65 – 0.79), respectively. Local tumor control was negatively associated with PTV volume (p = 0.007) and was a significant predictor of OS (HR 0.57, 95% CI 0.33 - 0.98, p = 0.04). Symptomatic radiation necrosis occurred in 3 patients (7%).

Conclusions

HR is well tolerated in both new and recurrent, previously irradiated intact or resected brain metastases. Local control is negatively associated with PTV volume and a significant predictor of overall survival, suggesting a need for dose escalation when using HR for large intracranial lesions.

Innovative therapeutic strategies in the treatment of brain metastases

Brain metastases (BM) are the most common intracranial tumors and their incidence is increasing. Untreated brain metastases are associated with a poor prognosis and a poor performance status. Metastasis development involves the migration of a cancer cell from the bulk tumor into the surrounding tissue, extravasation from the blood into tissue elsewhere in the body, and formation of a secondary tumor. In the recent past, important results have been obtained in the management of patients affected by BM, using surgery, radiation therapy, or both. Conventional chemotherapies have generally produced disappointing results, possibly due to their limited ability to penetrate the blood-brain barrier. The advent of new technologies has led to the discovery of novel molecules and pathways that have better depicted the metastatic process. Targeted therapies such as bevacizumab, erlotinib, gefitinib, sunitinib and sorafenib, are all licensed and have demonstrated improved survival in patients with metastatic disease. In this review, we will report current data on targeted therapies. A brief review about brain metastatic process will be also presented.

Ultrasound-mediated blood-brain/blood-tumor barrier disruption improves outcomes with trastuzumab in a breast cancer brain metastasis model

Trastuzumab has shown positive results in many patients with metastatic HER2-positive breast cancer, but it is less effective for controlling metastases in the CNS, which remains a site of relapse. The poor prognosis for patients with brain metastases is thought to be largely due to the presence of the blood-brain barrier (BBB) that prevents delivery of most drugs to the CNS and to the heterogeneous and limited permeability of the blood-tumor barrier (BTB). Focused ultrasound (FUS) bursts combined with circulating microbubbles can temporarily permeabilize both the BBB and the BTB. This technique has been investigated as a potential noninvasive method for targeted drug delivery in the brain. Here, we investigated whether BBB/BTB permeabilization in the tumor and surrounding brain tissue induced by FUS and microbubbles can slow tumor growth and improve survival in a breast cancer brain metastases model. HER2/neu-positive human breast cancer cells (BT474) were inoculated in the brains of 41 nude (nu/nu) rats. Animals in the treatment group received six weekly treatments of BTB/BBB permeabilization under MRI guidance combined with IV administration of trastuzumab (2 mg/kg). Tumor growth and survival rates were monitored via MRI for seven weeks after sonication. Starting at week seven and continuing through the end of the study, the mean tumor volume of the FUS+trastuzumab group was significantly (P<0.05) less than those of the three control groups (no treatment, FUS alone, trastuzumab alone). Furthermore, in four out of 10 rats treated with FUS+trastuzumab, the tumor appeared to be completely resolved in MRI, an outcome which was not observed in any of the 31 rats in three control groups. Trastuzumab improved median survival by 13% compared to the no treatment group, a difference which was significant (P=0.044). Treatment with FUS+trastuzumab produced the most significant benefit compared to the no-treatment controls (P=0.0084). More than half (6/10) animals survived at the study endpoint, leading to a median survival time greater than 83 days (at least 32% longer than the untreated control group). Overall, this work suggests that BBB/BTB permeabilization induced by FUS and microbubbles can improve outcomes in breast cancer brain metastases.

Brain metastases research 1990-2010: pattern of citation and systematic review of highly cited articles

BACKGROUND

High and continuously increasing research activity related to different aspects of prevention, prediction, diagnosis and treatment of brain metastases has been performed between 1990 and 2010. One of the major databases contains 2695 scientific articles that were published during this time period. Different measures of impact, visibility, and quality of published research are available, each with its own pros and cons. For this overview, article citation rate was chosen.

RESULTS

Among the 10 most cited articles, 7 reported on randomized clinical trials. Nine covered surgical or radiosurgical approaches and the remaining one a widely adopted prognostic score. Overall, 30 randomized clinical trials were published between 1990 and 2010, including those with phase II design and excluding duplicate publications, for example, after longer followup or with focus on secondary endpoints. Twenty of these randomized clinical trials were published before 2008. Their median number of citations was 110, range 13-1013, compared to 5-6 citations for all types of publications. Annual citation rate appeared to gradually increase during the first 2-3 years after publication before reaching high levels.

CONCLUSIONS

A large variety of preclinical and clinical topics achieved high numbers of citations. However, areas such as quality of life, side effects, and end-of-life care were underrepresented. Efforts to increase their visibility might be warranted.

Gamma knife surgery for brain metastases from ovarian cancer

Background

Brain metastases from ovarian cancer are rare, but their incidence is increasing. The purpose of this study was to investigate the characteristics of brain metastases from ovarian cancer, and to assess the efficacy of treatment with gamma knife surgery (GKS).

Methods

A retrospective review was performed of patients with brain metastases from ovarian cancer who were treated at the Tokyo Gamma Unit Center from 2006 to 2010.

Results

Sixteen patients were identified. Their median age at diagnosis of brain metastases was 56.5 years, the median interval from diagnosis of ovarian cancer to brain metastases was 27.5 months, and the median number of brain metastases was 2. The median Karnofsky Performance Score (KPS) at the first GKS was 80. The median survival following diagnosis of brain metastases was 12.5 months, and 6-month and 1-year survival rates were 75 % and 50 %, respectively. The tumor control rate was 86.4 %. The KPS (<80 vs ≥80) and total volume of brain metastases (<10 cm³ vs ≥10 cm³) were significantly associated with survival according to a univariate analysis (p = 0.004 and p = 0.02, respectively).

Conclusions

The results of this study suggest that GKS is an effective remedy and acceptable choice for the control of brain metastases from ovarian cancer.

A prospective pilot study of two-session Gamma Knife surgery for large metastatic brain tumors

The purpose of this prospective study is to evaluate the efficacy and limitations of two-session Gamma Knife radiosurgery (GKS) alone for large metastatic brain tumors. Inclusion criteria were as follows: (i) patients with large metastatic brain tumors (volume >15 cm(3) in the supratentorial region or >10 cm(3) in the infratentorial region), and (ii) tumors not causing clinical signs of impending cerebral herniation. Twenty-eight lesions in 27 consecutive patients (18 men and 9 women, age range 32 to 88 years, median age 65 years) were included in this study. The radiosurgical protocol was as follows: 20-30 Gy given in two fractions 3-4 weeks apart. The local tumor control rate and the overall survival rate were calculated by using the Kaplan-Meier method. Median tumor volumes were 17.8 cm(3) at first GKS and 9.7 cm(3) at second GKS. Median follow-up time was 8.9 months. The local control rate was 85 % at 6 months and 61 % at 12 months. The overall survival rate after GKS was 63 % at 6 months and 45 % at 12 months. The 1-year rate of prevention of neurological death was maintained at 78 %. Mean Karnofsky performance status (KPS) improved from 61 [95 % confidence interval (CI), 57-71] at first GKS to 80 (95 % CI, 74-85) at second GKS; the best follow-up mean KPS was 85 (95 % CI, 78-91) (p < 0.001). Local tumor recurrence necessitated craniotomy in two patients and repeat GKS in three patients. Seventeen patients died, and the causes of death were as follows: 3 from local progression, 2 from meningeal carcinomatosis, and 12 from progression of the primary tumor. Delayed symptomatic perilesional edema developed in one patient and eventually resolved with conservative treatment. Two-session GKS for large brain metastases appears to be an effective treatment in terms of both local tumor control and neurological palliation with minimal treatment-related morbidity. These data suggest that two-session GKS could be used as an alternative to surgical resection of large tumors in patients with significant comorbidity and/or at an advanced age. The optimum regimen for dose and fraction schedule remains to be established.

Clinical commissioning and use of the Novalis Tx linear accelerator for SRS and SBRT

The purpose of this study was to perform comprehensive measurements and testing of a Novalis Tx linear accelerator, and to develop technical guidelines for com-missioning from the time of acceptance testing to the first clinical treatment. The Novalis Tx (NTX) linear accelerator is equipped with, among other features, a high-definition MLC (HD120 MLC) with 2.5 mm central leaves, a 6D robotic couch, an optical guidance positioning system, as well as X-ray-based image guidance tools to provide high accuracy radiation delivery for stereotactic radiosurgery and stereotactic body radiation therapy procedures. We have performed extensive tests for each of the components, and analyzed the clinical data collected in our clinic. We present technical guidelines in this report focusing on methods for: (1) efficient and accurate beam data collection for commissioning treatment planning systems, including small field output measurements conducted using a wide range of detectors; (2) commissioning tests for the HD120 MLC; (3) data collection for the baseline characteristics of the on-board imager (OBI) and ExacTrac X-ray (ETX) image guidance systems in conjunction with the 6D robotic couch; and (4) end-to-end testing of the entire clinical process. Established from our clinical experience thus far, recommendations are provided for accurate and efficient use of the OBI and ETX localization systems for intra- and extracranial treatment sites. Four results are presented. (1) Basic beam data measurements: Our measurements confirmed the necessity of using small detectors for small fields. Total scatter factors varied significantly (30% to approximately 62%) for small field measurements among detectors. Unshielded stereotactic field diode (SFD) overestimated dose by ~ 2% for large field sizes. Ion chambers with active diameters of 6 mm suffered from significant volume averaging. The sharpest profile penumbra was observed for the SFD because of its small active diameter (0.6 mm). (2) MLC commissioning: Winston Lutz test, light/radiation field congruence, and Picket Fence tests were performed and were within criteria established by the relevant task group reports. The measured mean MLC transmission and dynamic leaf gap of 6 MV SRS beam were 1.17% and 0.36 mm, respectively. (3) Baseline characteristics of OBI and ETX: The isocenter localization errors in the left/right, posterior/anterior, and superior/inferior directions were, respectively, -0.2 ± 0.2 mm, -0.8 ± 0.2 mm, and -0.8 ± 0.4 mm for ETX, and 0.5 ± 0.7 mm, 0.6 ± 0.5 mm, and 0.0 ± 0.5 mm for OBI cone-beam computed tomography. The registration angular discrepancy was 0.1 ± 0.2°, and the maximum robotic couch error was 0.2°. (4) End-to-end tests: The measured isocenter dose differences from the planned values were 0.8% and 0.4%, measured respectively by an ion chamber and film. The gamma pass rate, measured by EBT2 film, was 95% (3% DD and 1 mm DTA). Through a systematic series of quantitative commissioning experiments and end-to-end tests and our initial clinical experience, described in this report, we demonstrate that the NTX is a robust system, with the image guidance and MLC requirements to treat a wide variety of sites - in particular for highly accurate delivery of SRS and SBRT-based treatments.

Local control of newly diagnosed and distally recurrent, low-volume brain metastases with fixed-dose (20 gy) gamma knife radiosurgery

BACKGROUND

Metastases to the brain occur in 20% to 30% of patients with cancer and have been identified on autopsy in as many as 50% of patients.

OBJECTIVE

To analyze the efficacy of 20-Gy Gamma Knife radiosurgery (GKR) as initial treatment in patients with 1 to 3 brain metastases ≤ 2 cm in greatest diameter.

METHODS

A retrospective analysis of 114 consecutive adults with Karnofsky performance status ≥ 60 who received GKR for 1 to 3 brain metastases ≤ 2 cm in size was performed. Five patients lacked detailed follow-up and were excluded, leaving 109 for outcome analysis (34 men and 75 women; median age, 61.2 years). All metastases received 20 Gy to the 50% isodose line.

RESULTS

One hundred nine patients underwent treatment of 164 metastases at initial GKR. Twenty-six patients (23.9%) were alive at last follow-up (median time, 29.9 months; range, 6.6 months to 7.8 years). The median overall survival was 13.8 months (range, 1 day to 7.6 years). Among the 52 patients with distant failure, 33 patients received 20 Gy to 95 new lesions. A total of 259 metastases received 20 Gy, and 4 patients lacked imaging follow-up secondary to death before posttreatment imaging. Local failure occurred in 17 of 255 treated lesions (6.7%), yielding an overall local control rate of 93.3%. Actuarial local control at 6, 12, 24, and 36 months was 96%, 93%, 89%, and 88%, respectively. Permanent neurological complications occurred in 3 patients (2.8%).

CONCLUSION

Among patients with 1 to 3 brain metastases ≤ 2 cm in size who have not received whole-brain radiation therapy, GKR with 20 Gy provides high rates of local control with low morbidity and excellent neurological symptom-free survival.

Radiographic response of brain metastasis after linear accelerator radiosurgery

BACKGROUND

Radiographic response of brain metastasis to stereotactic radiosurgery (SRS) over time has not been well characterized. Being able to predict SRS-induced changes in tumor size over time may allow improved counseling of patients and potentially earlier recognition of poor response to SRS.

OBJECTIVE

To quantify the rate of change in size of metastatic brain tumors after treatment with a linear accelerator (LINAC) SRS.

METHODS

We performed a retrospective analysis of patients with single metastatic brain tumors treated with LINAC SRS at the University of Florida between 1992 and 2009 who had at least one MRI after treatment. A total of 218 patients with 406 follow-up MRI scans were included in the study. Tumor area was calculated by measuring the largest tumor area on axial imaging and using the equation for area of an ellipse. Primary outcome was percent change in tumor size. The contribution of several factors including gender, primary tumor histology, synchronous or asynchronous presentation, prior treatment, primary tumor control, and SRS dose were examined using multivariate analysis.

RESULTS

Mean patient age was 58.3 years (range 4-86), and 48.6% of patients were female. Sixty-three percent of patients had primary tumor control and 70.6% had asynchronous presentation of their brain metastases. SRS peripheral dose range was 1,000-2,250 cGy with a median of 1,750 cGy. The mean percent size change was -22.6% with a mean rate of change of -7.0% per month. The median percent change was -49.7% with a median rate of change of -8.8% per month. The median follow-up was 4.8 months (range 0.3-52.5). Female gender and melanoma histology were found to be significant predictors of an increase in tumor size. Lack of previous surgical resection was a significant predictor of a decrease in tumor size after SRS. Other factors tested with multivariate analysis, including age, synchronicity of presentation, dose, dose volume, Karnofsky performance score, and primary tumor control, were not significant in predicting tumor size change after SRS.

CONCLUSION

In this study, brain metastases decreased in size by a median of 50% for a median follow-up of 4.8 months after SRS. The overall rate of decrease was 9% per month after treatment with SRS. Melanoma histology was a predictor of poor tumor control.