The impact of whole-brain radiation therapy on the long-term control and morbidity of patients surviving more than one year after gamma knife radiosurgery for brain metastases

Delayed Imaging Changes 18 Months or Longer After Stereotactic Radiosurgery for Brain Metastases: Necrosis or Progression

OBJECTIVE

Imaging changes after stereotactic radiosurgery (SRS) can occur for years after treatment, although the available data on the incidence of tumor progression and adverse radiation effects (ARE) are generally limited to the first 2 years after treatment.

METHODS

A single-institution retrospective review was conducted of patients who had >18 months of imaging follow-up available. Patients who had ≥1 metastatic brain lesions treated with Gamma Knife SRS were assessed for the time to radiographic progression. Those with progression ≥18 months after the initial treatment were included in the present study. The lesions that progressed were characterized as either ARE or tumor progression based on the tissue diagnosis or imaging characteristics over time.

RESULTS

The cumulative incidence of delayed imaging radiographic progression was 35% at 5 years after the initial SRS. The cumulative incidence curves of the time to radiographic progression for lesions determined to be ARE and lesions determined to be tumor progression were not significantly different statistically. The cumulative incidence of delayed ARE and delayed tumor progression was 17% and 16% at 5 years, respectively. Multivariate analysis indicated that the number of metastatic brain lesions present at the initial SRS was the only factor associated with late radiographic progression.

CONCLUSIONS

The timing of late radiographic progression does not differ between ARE and tumor progression. The number of metastatic brain lesions at the initial SRS is a risk factor for late radiographic progression.

Efficacy of Stereotactic Radiosurgery as Single or Combined Therapy for Brain Metastasis: A Systematic Review and Meta-Analysis

To determine the efficacy of stereotactic radiosurgery (SRS) in treating patients with brain metastases (BMs), a network meta-analysis (NMA) of randomized controlled trials (RCTs) and a direct comparison of cohort studies were performed. Relevant literature regarding the effectiveness of SRS alone and in combination with whole-brain radiotherapy (WBRT) and surgery was retrieved using systematic database searches up to April 2019. The patterns of overall survival (OS), one-year OS, progression-free survival (PFS), one-year local brain control (LBC), one-year distant brain control (DBC), neurological death (ND), and complication rate were analyzed. A total of 18 RCTs and 37 cohorts were included in the meta-analysis. Our data revealed that SRS carried a better OS than SRS+WBRT (p= 0.048) and WBRT (p= 0.041). Also, SRS+WBRT demonstrated a significantly improved PFS, LBC, and DBC compared to WBRT alone and SRS alone. Finally, SRS achieved the same LBC as high as surgery, but intracranial relapse occurred considerably more frequently in the absence of WBRT. However, there were not any significant differences in ND and toxicities between SRS and other groups. Therefore, SRS alone may be a better alternative since increased patient survival may outweigh the increased risk of brain tumor recurrence associated with it.

Multi-Institutional Dosimetric Evaluation of Modern Day Stereotactic Radiosurgery (SRS) Treatment Options for Multiple Brain Metastases

Purpose/Objectives: There are several popular treatment options currently available for stereotactic radiosurgery (SRS) of multiple brain metastases: ⁶⁰Co sources and cone collimators around a spherical geometry (GammaKnife), multi-aperture dynamic conformal arcs on a linac (BrainLab Elements™ v1.5), and volumetric arc therapy on a linac (VMAT) calculated with either the conventional optimizer or with the Varian HyperArc™ solution. This study aimed to dosimetrically compare and evaluate the differences among these treatment options in terms of dose conformity to the tumor as well as dose sparing to the surrounding normal tissues. Methods and Materials: Sixteen patients and a total of 112 metastases were analyzed. Five plans were generated per patient: GammaKnife, Elements, HyperArc-VMAT, and two Manual-VMAT plans to evaluate different treatment planning styles. Manual-VMAT plans were generated by different institutions according to their own clinical planning standards. The following dosimetric parameters were extracted: RTOG and Paddick conformity indices, gradient index, total volume of brain receiving 12Gy, 6Gy, and 3Gy, and maximum doses to surrounding organs. The Wilcoxon signed rank test was applied to evaluate statistically significant differences (p < 0.05). Results: For targets ≤ 1 cm, GammaKnife, HyperArc-VMAT and both Manual-VMAT plans achieved comparable conformity indices, all superior to Elements. However, GammaKnife resulted in the lowest gradient indices at these target sizes. HyperArc-VMAT performed similarly to GammaKnife for V_12Gy parameters. For targets ≥ 1 cm, HyperArc-VMAT and Manual-VMAT plans resulted in superior conformity vs. GammaKnife and Elements. All SRS plans achieved clinically acceptable organs-at-risk dose constraints. Beam-on times were significantly longer for GammaKnife. Manual-VMAT_A and Elements resulted in shorter delivery times relative to Manual-VMAT_B and HyperArc-VMAT. Conclusion: The study revealed that Manual-VMAT and HyperArc-VMAT are capable of achieving similar low dose brain spillage and conformity as GammaKnife, while significantly minimizing beam-on time. For targets smaller than 1 cm in diameter, GammaKnife still resulted in superior gradient indices. The quality of the two sets of Manual-VMAT plans varied greatly based on planner and optimization constraint settings, whereas HyperArc-VMAT performed dosimetrically superior to the two Manual-VMAT plans.

Advanced Magnetic Resonance Imaging Techniques in Management of Brain Metastases

Brain metastases are the most common intracranial tumors and occur in 20–40% of all cancer patients. Lung cancer, breast cancer, and melanoma are the most frequent primary cancers to develop brain metastases. Treatment options include surgical resection, whole brain radiotherapy, stereotactic radiosurgery, and systemic treatment such as targeted or immune therapy. Anatomical magnetic resonance imaging (MRI) of the tumor (in particular post-Gadolinium T₁-weighted and T₂-weighted FLAIR) provide information about lesion morphology and structure, and are routinely used in clinical practice for both detection and treatment response evaluation for brain metastases. Advanced MRI biomarkers that characterize the cellular, biophysical, micro-structural and metabolic features of tumors have the potential to improve the management of brain metastases from early detection and diagnosis, to evaluating treatment response. Magnetic resonance spectroscopy (MRS), chemical exchange saturation transfer (CEST), quantitative magnetization transfer (qMT), diffusion-based tissue microstructure imaging, trans-membrane water exchange mapping, and magnetic susceptibility weighted imaging (SWI) are advanced MRI techniques that will be reviewed in this article as they pertain to brain metastases.

Comparison of WBRT alone, SRS alone, and their combination in the treatment of one or more brain metastases: Review and meta-analysis

Whole brain radiotherapy has been a standard treatment of brain metastases. Stereotactic radiosurgery provides more focal and aggressive radiation and normal tissue sparing but worse local and distant control. This meta-analysis was performed to assess and compare the effectiveness of whole brain radiotherapy alone, stereotactic radiosurgery alone, and their combination in the treatment of brain metastases based on randomized controlled trial studies. Electronic databases (PubMed, MEDLINE, Embase, and Cochrane Library) were searched to identify randomized controlled trial studies that compared treatment outcome of whole brain radiotherapy and stereotactic radiosurgery. This meta-analysis was performed using the Review Manager (RevMan) software (version 5.2) that is provided by the Cochrane Collaboration. The data used were hazard ratios with 95% confidence intervals calculated for time-to-event data extracted from survival curves and local tumor control rate curves. Odds ratio with 95% confidence intervals were calculated for dichotomous data, while mean differences with 95% confidence intervals were calculated for continuous data. Fixed-effects or random-effects models were adopted according to heterogeneity. Five studies (n = 763) were included in this meta-analysis meeting the inclusion criteria. All the included studies were randomized controlled trials. The sample size ranged from 27 to 331. In total 202 (26%) patients with whole brain radiotherapy alone, 196 (26%) patients receiving stereotactic radiosurgery alone, and 365 (48%) patients were in whole brain radiotherapy plus stereotactic radiosurgery group. No significant survival benefit was observed for any treatment approach; hazard ratio was 1.19 (95% confidence interval: 0.96-1.43, p = 0.12) based on three randomized controlled trials for whole brain radiotherapy only compared to whole brain radiotherapy plus stereotactic radiosurgery and hazard ratio was 1.03 (95% confidence interval: 0.82-1.29, p = 0.81) for stereotactic radiosurgery only compared to combined approach. Local control was best achieved when whole brain radiotherapy was combined with stereotactic radiosurgery. Hazard ratio 2.05 (95% confidence interval: 1.36-3.09, p = 0.0006) and hazard ratio 1.84 (95% confidence interval: 1.26-2.70, p = 0.002) were obtained from comparing whole brain radiotherapy only and stereotactic radiosurgery only to whole brain radiotherapy + stereotactic radiosurgery, respectively. No difference in adverse events for treatment difference; odds ratio 1.16 (95% confidence interval: 0.77-1.76, p = 0.48) and odds ratio 0.92 (95% confidence interval: 0.59-1.42, p = 71) for whole brain radiotherapy + stereotactic radiosurgery versus whole brain radiotherapy only and whole brain radiotherapy + stereotactic radiosurgery versus stereotactic radiosurgery only, respectively. Adding stereotactic radiosurgery to whole brain radiotherapy provides better local control as compared to whole brain radiotherapy only and stereotactic radiosurgery only with no difference in radiation related toxicities.

A method to improve dose gradient for robotic radiosurgery

For targets with substantial volume, collimators of relatively large size are usually selected to minimize the treatment time in robotic radiosurgery. Their large penumbrae may adversely affect the dose gradient around the target. In this study, we implement and evaluate an inner‐shell planning method to increase the dose gradient and reduce dose to normal tissues. Ten patients previously treated with CyberKnife M6 system were randomly selected with the only criterion being that PTV be larger than 2 cm3. A new plan was generated for each patient in which the PTV was split into two regions: a 5 mm inner shell and a core, and a 7.5 mm Iris collimator was exclusively applied to the shell, with other appropriate collimators applied to the core depending on its size. The optimization objective, functions, and constraints were the same as in the corresponding clinical plan. The results were analyzed for V12 Gy, V9 Gy, V5 Gy, and gradient index (GI). Volume reduction was found for the inner‐shell method at all studied dose levels as compared to the clinical plans. The absolute dose‐volume reduction ranged from 0.05 cm3 to 18.5 cm3 with a mean of 5.6 cm3 for 12 Gy, from 0.2 cm3 to 38.1 cm3 with a mean of 9.8 cm3 for 9 Gy, and from 1.5 cm3 to 115.7 cm3 with a mean of 24.8 cm3 for 5 Gy, respectively. The GI reduction ranged from 3.2% to 23.6%, with a mean of 12.6%. Paired t‐test for GI has a p‐value of 0.0014. The range for treatment time increase is from ‐3 min to 20 min, with a mean of 7.0 min. We conclude that irradiating the PTV periphery exclusively with the 7.5 mm Iris collimator, rather than applying mixed collimators to the whole PTV, can substantially improve the dose gradient, while maintaining good coverage, conformity, and reasonable treatment time.

PACS number: 87.55.de

Long-term risk of radionecrosis and imaging changes after stereotactic radiosurgery for brain metastases

Radionecrosis is a well-characterized effect of stereotactic radiosurgery (SRS) and is occasionally associated with serious neurologic sequelae. Here, we investigated the incidence of and clinical variables associated with the development of radionecrosis and related radiographic changes after SRS for brain metastases in a cohort of patients with long-term follow up. 271 brain metastases treated with single-fraction linear accelerator-based SRS were analyzed. Radionecrosis was diagnosed either pathologically or radiographically. Univariate and multivariate Cox regression was performed to determine the association between radionecrosis and clinical factors available prior to treatment planning. After median follow up of 17.2 months, radionecrosis was observed in 70 (25.8%) lesions, including 47 (17.3%) symptomatic cases. 22 of 70 cases (31.4%) were diagnosed pathologically and 48 (68.6%) were diagnosed radiographically. The actuarial incidence of radionecrosis was 5.2% at 6 months, 17.2% at 12 months and 34.0% at 24 months. On univariate analysis, radionecrosis was associated with maximum tumor diameter (HR 3.55, p < 0.001), prior whole brain radiotherapy (HR 2.21, p = 0.004), prescription dose (HR 0.56, p = 0.02) and histology other than non-small cell lung, breast or melanoma (HR 1.85, p = 0.04). On multivariate analysis, only maximum tumor diameter (HR 3.10, p < 0.001) was associated with radionecrosis risk. This data demonstrates that with close imaging follow-up, radionecrosis after single-fraction SRS for brain metastases is not uncommon. Maximum tumor diameter on pre-treatment MR imaging can provide a reliable estimate of radionecrosis risk prior to treatment planning, with the greatest risk among tumors measuring >1 cm.

Potential role for LINAC-based stereotactic radiosurgery for the treatment of 5 or more radioresistant melanoma brain metastases

OBJECT

Linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) is a treatment option for patients with melanoma in whom brain metastases have developed. Very limited data are available on treating patients with ≥5 lesions. The authors sought to determine the effectiveness of SRS in patients with ≥5 melanoma brain metastases.

METHODS

A retrospective analysis of metastatic melanoma treated with SRS in a single treatment session for ≥5 lesions was performed. Magnetic resonance imaging studies were reviewed post-SRS to evaluate local control (LC). Disease progression on imaging was defined using the 2009 Response Evaluation Criteria in Solid Tumors (RECIST). Survival curves were calculated from the date of brain metastases diagnosis or the date of SRS by using the Kaplan-Meier (KM) method. Univariate and multivariate analysis (UVA and MVA, respectively) were performed using the Cox proportional-hazards model.

RESULTS

The authors identified 149 metastatic brain lesions treated in 28 patients. The median patient age was 60.5 years (range 38-83 years), and the majority of patients (24 [85.7%]) had extracranial metastases. Four patients (14.3%) had received previous whole-brain radiotherapy (WBRT), and 11 (39.3%) had undergone previous SRS. The median planning target volume (PTV) was 0.34 cm3 (range 0.01-12.5 cm3). Median follow-up was 6.3 months (range 1-46 months). At the time of treatment, 7% of patients were categorized as recursive partitioning analysis (RPA) Class I, 89% as RPA Class II, and 4% as RPA Class III. The rate of local failure was 11.4%. Kaplan-Meier LC estimates at 6 and 12 months were 91.3% and 82.2%, respectively. A PTV volume≥0.34 cm3 was a significant predictor of local failure on UVA (HR 16.1, 95% CI 3.2-292.6, p<0.0001) and MVA (HR 14.8, 95% CI 3.0-268.5, p=0.0002). Sixteen patients (57.1%) were noted to have distant failure in the brain with a median time to failure of 3 months (range 1-15 months). Nine patients with distant failures received WBRT, and 7 received additional SRS. Median overall survival (OS) was 9.4 and 7.6 months from the date of brain metastases diagnosis and the date of SRS, respectively. The KM OS estimates at 6 and 12 months were 57.8% and 28.2%, respectively, from the time of SRS treatment. The RPA class was a significant predictor of KM OS estimates from the date of treatment (p=0.02). Patients who did not receive WBRT after SRS treatment had decreased OS on MVA (HR 3.5, 95% CI 1.1-12.0, p=0.03), and patients who did not receive WBRT prior to SRS had improved OS (HR 0.11, 95% CI 0.02-0.53, p=0.007).

CONCLUSIONS

Stereotactic radiosurgery for ≥5 lesions appears to be effective for selected patients with metastatic melanoma, offering excellent LC. This is particularly important for patients as new targeted systemic agents are improving outcomes but still have limited efficacy within the central nervous system.

Decision analysis of stereotactic radiation surgery versus stereotactic radiation surgery and whole-brain radiation therapy for 1 to 3 brain metastases

PURPOSE

Although whole-brain radiation therapy (WBRT) is effective for controlling intracranial disease, it is also associated with neurocognitive side effects. It is unclear whether a theoretically improved quality of life after stereotactic radiation surgery (SRS) alone relative to that after SRS with adjuvant WBRT would justify the omission of WBRT, given the higher risk of intracranial failure. This study compares SRS alone with SRS and WBRT, to evaluate the theoretical benefits of intracranial tumor control with adjuvant WBRT against its possible side effects, using quality-adjusted life expectancy (QALE) as a primary endpoint.

METHODS AND MATERIALS

A Markov decision analysis model was used to compare QALE in a cohort of patients with 1 to 3 brain metastases and Karnofsky performance status of at least 70. Patients were treated with SRS alone or with SRS immediately followed by WBRT. Patients treated with SRS alone underwent surveillance magnetic resonance imaging and received salvage WBRT if they developed intracranial relapse. All patients whose cancer relapsed after WBRT underwent simulation as dying of intracranial progression. Model parameters were estimated from published literature.

RESULTS

Treatment with SRS yielded 6.2 quality-adjusted life months (QALMs). The addition of initial WBRT reduced QALE by 1.2 QALMs. On one-way sensitivity analysis, the model was sensitive only to a single parameter, the utility associated with the state of no evidence of disease after SRS alone. At values greater than 0.51, SRS alone was preferred.

CONCLUSIONS

In general, SRS alone is suggested to have improved quality of life in patients with 1 to 3 brain metastases compared to SRS and immediate WBRT. Our results suggest that immediate treatment with WBRT after SRS can be reserved for patients who would have a poor performance status regardless of treatment. These findings are stable under a wide range of assumptions.

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.

It Is Time to Reevaluate the Management of Patients With Brain Metastases

There are many elements to the science that drives the clinical care of patients with brain metastases. Although part of an understanding that continues to evolve, a number of key historical misconceptions remain that commonly drive physicians' and researchers' attitudes and approaches. By understanding how these relate to current practice, we can better comprehend our available science to provide both better research and care. These past misconceptions include: Misconception 1: Once a primary cancer spreads to the brain, the histology of that primary tumor does not have much impact on response to chemotherapy, sensitivity to radiation, risk of further brain relapse, development of additional metastatic lesions, or survival. All tumor primary histologies are the same once they spread to the brain. They are the same in terms of the number of tumors, radiosensitivity, chemoresponsiveness, risk of further brain relapse, and survival. Misconception 2: The number of brain metastases matters. This number matters in terms of subsequent brain relapse, survival, and cognitive dysfunction; the precise number of metastases can also be used as a limit in determining which patients might be eligible for a particular treatment option. Misconception 3: Cancer in the brain is always a diffuse problem due to the presence of micrometastases. Misconception 4: Whole-brain radiation therapy invariably causes disabling cognitive dysfunction if a patient lives long enough. Misconception 5: Most brain metastases are symptomatic. Thus, it is not worth screening patients for brain metastases, especially because the impact on survival is minimal. The conduct and findings of past clinical research have led to conceptions that affect clinical care yet appear limiting.

Neurologic complications of lung cancer

Neurologic complications of lung cancer are a frequent cause of morbidity and mortality. Tumor metastasis to the brain parenchyma is the single most common neurologic complication of lung cancer, of any histologic subtype. The goal of radiation therapy and in some cases surgical resection for patients with brain metastases is to improve or maintain neurologic function, and to achieve local control of the brain lesion(s). Metastasis of lung cancer to the spinal epidural space requires urgent evaluation and treatment. Early diagnosis and modern surgical and radiotherapy techniques improve neurologic outcome for most patients. Leptomeningeal metastasis is a less common but ominous occurrence in patients with lung cancer. Lung carcinomas can also occasionally metastasize to the brachial plexus, skull base, dura, or pituitary. Paraneoplastic neurologic disorders are uncommon but important complications of lung carcinoma, and are generally the presenting feature of the tumor. Paraneoplastic disorders are believed to be caused by an autoimmune humoral or cellular attack against shared "onconeural" antigens. The most frequent paraneoplastic disorders in patients with lung cancer are Lambert-Eaton myasthenic syndrome, and multifocal paraneoplastic encephalomyelitis, both mainly occurring in association with small-cell lung carcinoma. There is a variety of other paraneoplastic disorders affecting the central and peripheral nervous systems. Some affected patients have a good neurologic outcome, while others are left with severe permanent neurologic disability.

The accuracy of predicting survival in individual patients with cancer

OBJECT

Estimating survival time in cancer patients is crucial for clinicians, patients, families, and payers. To provide appropriate and cost-effective care, various data sources are used to provide rational, reliable, and reproducible estimates. The accuracy of such estimates is unknown.

METHODS

The authors prospectively estimated survival in 150 consecutive cancer patients (median age 62 years) with brain metastases undergoing radiosurgery. They recorded cancer type, number of brain metastases, neurological presentation, extracranial disease status, Karnofsky Performance Scale score, Recursive Partitioning Analysis class, prior whole-brain radiotherapy, and synchronous or metachronous presentation. Finally, the authors asked 18 medical, radiation, or surgical oncologists to predict survival from the time of treatment.

RESULTS

The actual median patient survival was 10.3 months (95% CI 6.4-14). The median physician-predicted survival was 9.7 months (neurosurgeons = 11.8 months, radiation oncologists = 11.0 months, and medical oncologist = 7.2 months). For patients who died before 10 months, both neurosurgeons and radiation oncologists generally predicted survivals that were more optimistic and medical oncologists that were less so, although no group could accurately predict survivors alive at 14 months. All physicians had individual patient survival predictions that were incorrect by as much as 12-18 months, and 14 of 18 physicians had individual predictions that were in error by more than 18 months. Of the 2700 predictions, 1226 (45%) were off by more than 6 months and 488 (18%) were off by more than 12 months.

CONCLUSIONS

Although crucial, predicting the survival of cancer patients is difficult. In this study all physicians were unable to accurately predict longer-term survivors. Despite valuable clinical data and predictive scoring techniques, brain and systemic management often led to patient survivals well beyond estimated survivals.

The role of stereotactic radiosurgery for multiple brain metastases in stable systemic disease: a review of the literature

BACKGROUND

Cancer patients with brain metastases display a median survival of only 1 to 2 months if left untreated. Although whole-brain radiation therapy (WBRT) has lengthened median patient survival, the long-term neurotoxic effects of WBRT have become a deterrent to its use in the context of stable systemic disease. Therefore, it is important to identify patients who might benefit from stereotactic radiosurgery (SRS) in order to delay or avoid WBRT. Here we present a review of the literature to elucidate the role of SRS in patients with multiple brain metastases.

METHODS

MEDLINE search for English-language articles from 1998 to 2012 describing survival or neurocognitive functioning of patients with multiple brain metastases treated with SRS, WBRT, or a combination.

RESULTS

SRS monotherapy yields an equivalent survival with low risk of long-term neurotoxicity, but higher rate of recurrence, compared to WBRT or combined radiotherapy. Patients with ≤4 brain metastases or KPS ≥ 80 are expected to survive significantly longer than the onset time of prominent WBRT-induced neurocognitive decline.

CONCLUSIONS

SRS, administered alone or adjuvant to surgical resection of symptomatic metastases, is preferred for patients with ≤4 brain metastases or KPS ≥ 80 to delay or avoid WBRT. WBRT can then be employed in the event of recurrence. WBRT with or without resection is preferred for patients with ≥5 brain metastases and KPS < 80, due to these patients' shorter survival and increased recurrence risk. SRS boost treatments can then be used in the event of poor tumor response or progression.

Stereotactic radiosurgery in the treatment of brain metastases: the current evidence

Chemotherapy has made substantial progress in the therapy of systemic cancer, but the pharmacological efficacy is insufficient in the treatment of brain metastases. Fractionated whole brain radiotherapy (WBRT) has been a standard treatment of brain metastases, but provides limited local tumor control and often unsatisfactory clinical results. Stereotactic radiosurgery using Gamma Knife, Linac or Cyberknife has overcome several of these limitations, which has influenced recent treatment recommendations. This present review summarizes the current literature of single session radiosurgery concerning survival and quality of life, specific responses, tumor volumes and numbers, about potential treatment combinations and radioresistant metastases. Gamma Knife and Linac based radiosurgery provide consistent results with a reproducible local tumor control in both single and multiple brain metastases. Ideally minimum doses of ≥18Gy are applied. Reported local control rates were 90-94% for breast cancer metastases and 81-98% for brain metastases of lung cancer. Local tumor control rates after radiosurgery of otherwise radioresistant brain metastases were 73-90% for melanoma and 83-96% for renal cell cancer. Currently, there is a tendency to treat a larger number of brain metastases in a single radiosurgical session, since numerous studies document high local tumor control after radiosurgical treatment of >3 brain metastases. New remote brain metastases are reported in 33-42% after WBRT and in 39-52% after radiosurgery, but while WBRT is generally applied only once, radiosurgery can be used repeatedly for remote recurrences or new metastases after WBRT. Larger metastases (>8-10cc) should be removed surgically, but for smaller metastases Gamma Knife radiosurgery appears to be equally effective as surgical tumor resection (level I evidence). Radiosurgery avoids the impairments in cognition and quality of life that can be a consequence of WBRT (level I evidence). High local efficacy, preservation of cerebral functions, short hospitalization and the option to continue a systemic chemotherapy are factors in favor of a minimally invasive approach with stereotactic radiosurgery.

Multiple gamma knife radiosurgery for multiple metachronous brain metastases associated with lung cancer : survival time

OBJECTIVE

We compared the survival time between patients with multiple gamma knife radiosurgery (GKRS) and patients with a single GKRS plus whole brain radiation therapy (WBRT), in patients with multiple metachronous brain metastases from lung cancer.

METHODS

From May 2006 to July 2010, we analyzed 31 patients out of 112 patients who showed multiple metachronous brain metastases. 20 out of 31 patients underwent multiple GKRS (group A) and 11 patients underwent a single GKRS plus WBRT (group B). We compared the survival time between group A and B. Kaplan-Meier method and Cox proportional hazards were used to analyze relationship between survival and 1) the number of lesions in each patient, 2) the average volume of lesions in each patient, 3) the number of repeated GKRS, and 4) the interval of development of new lesions, respectively.

RESULTS

Median survival time was 18 months (range 6-50 months) in group A and 6 months (range 3-18 months) in group B. Only the average volume of individual lesion (over 10 cc) was negatively related with survival time according to Kaplan-Meier method. Cox-proportional hazard ratio of each variable was 1.1559 for the number of lesions, 1.0005 for the average volume of lesions, 0.0894 for the numbers of repeated GKRS, and 0.5970 for the interval of development of new lesions.

CONCLUSION

This study showed extended survival time in group A compared with group B. Our result supports that multiple GKRS is of value in extending the survival time in patients with multiple metachronous brain metastases, and that the number of the lesions and the frequency of development of new lesions are not an obstacle in treating patients with GKRS.

Stereotactic radiosurgery with or without whole-brain radiotherapy for brain metastases: an update

Brain metastases are unfortunately a common occurrence in patients with cancer. Whole-brain radiation therapy (WBRT) is still considered the standard of care in the treatment of brain metastases. Stereotactic radiosurgery (SRS) offers the additional ability to treat tumors with relative sparing of normal brain tissue in a single fraction. While the addition of SRS to WBRT has been shown to improve survival and local tumor control in selected patients, the idea of deferring WBRT in order to avoid its effects on normal tissues and using SRS alone continues to generate significant discussion and interest. Three recent randomized trials from Japan, Europe and the MD Anderson Cancer Center (TX, USA) have attempted to address this issue. In this article, we update a previous review by discussing these trials to compare the outcomes for SRS alone versus SRS plus WBRT for limited metastases. We also discuss recent nonrandomized evidence for the use of SRS alone for oligometastatic disease.

Do patients with a limited number of brain metastases need whole-brain radiotherapy in addition to radiosurgery?

BACKGROUND

About 40% of patients with brain metastases have a very limited number of lesions and may be candidates for radiosurgery. Radiosurgery alone is superior to whole-brain radiotherapy (WBRT) alone for control of treated and new brain metastases. In patients with a good performance status, radiosurgery also resulted in better survival. However, the question is whether the results of radiosurgery alone can be further improved with additional WBRT.

METHODS

Information for this review was compiled by searching the PubMed and MEDLINE databases. Very important published meeting abstracts were also considered.

RESULTS

Based on both retrospective and prospective studies, the addition of WBRT to radiosurgery improved control of treated and new brain metastases but not survival. However, because a recurrence within the brain has a negative impact on neurocognitive function, it is important to achieve long-term control of brain metastases.

CONCLUSION

The addition of WBRT provides significant benefits. Further randomized studies including adequate assessment of neurocognitive function and a follow-up period of at least 2 years are needed to help customize the treatment for individual patients.

Radiosurgery to the postoperative surgical cavity: who needs evidence?

There is a growing interest in adjuvant radiosurgery after resection of hematogenous brain metastases. This is exemplified by the approximately 1000 cases reported in mainly retrospective series. These cases fall into four paradigms: adjuvant radiosurgery as an alternative to whole-brain radiotherapy (WBRT), radiosurgery neoadjuvant to the surgical resection, radiosurgery as an intensification of adjuvant WBRT, and adjuvant radiosurgery for patients having failed prior WBRT. These procedures seem well tolerated, with an approximate 5% risk of radiation necrosis. Although crude local control rates for each strategy seem improved over surgery alone, multiple biases make comparisons with standard WBRT difficult without prospective data. Because evidence lags behind clinical practice, an upcoming intergroup trial will aim to clarify the value of the most common tumor bed radiosurgery strategy by randomizing oligometastatic patients between adjuvant WBRT and adjuvant radiosurgery.

The role of surgery, radiosurgery and whole brain radiation therapy in the management of patients with metastatic brain tumors

Brain tumors constitute the most common intracranial tumor. Management of brain metastases has become increasingly complex as patients with brain metastases are living longer and more treatment options develop. The goal of this paper is to review the role of stereotactic radiosurgery (SRS), whole brain radiation therapy (WBRT), and surgery, in isolation and in combination, in the contemporary treatment of brain metastases. Surgery and SRS both offer management options that may help to optimize therapy in selected patients. WBRT is another option but can lead to late toxicity and suboptimal local control in longer term survivors. Improved prognostic indices will be critical for selecting the best therapies. Further prospective trials are necessary to continue to elucidate factors that will help triage patients to the proper brain-directed therapy for their cancer.

Clinical outcomes of stereotactic radiosurgery in the treatment of patients with metastatic brain tumors

BACKGROUND

Stereotactic radiosurgery (SRS) is a form of radiation therapy that delivers a focused, highly conformal dose of radiation to a single volume, while minimizing damage to the adjacent nervous tissue. The efficacy of SRS has been examined in the treatment of patients diagnosed with brain metastases due to the fact that it is capable of targeting any region in the brain and can irradiate multiple tumors in the same treatment setting in a noninvasive fashion.

METHODS

Modern literature was reviewed for studies on SRS in the treatment of patients with brain metastases.

RESULTS

After assessing patient age, Karnofsky Performance Score (KPS), control of primary cancer, presence of extracranial metastases, number of brain metastases, location of brain metastases, and size of brain metastases, SRS offers suitable patients a viable, less invasive treatment option. In patients with 1 to 4 brain metastases who have a KPS ≥70, the addition of SRS to whole-brain radiation therapy (WBRT) produces increased levels of survival and local tumor control when compared with patients treated with WBRT alone. The available evidence suggests that specific patients treated with SRS alone exhibit superior levels of survival and tumor control when compared with patients treated with WBRT alone. Further evidence in the form of a randomized trial is needed to confirm this observation. Questions remain regarding survival and tumor control in patient groups treated with SRS with or without WBRT. Recently published randomized evidence reported a survival advantage in patients treated with SRS alone. These data differ from other previously published randomized evidence, as well as several prospective and retrospective studies, which reported nonsignificant survival differences. Contrasting evidence also exists pertaining to local and distant tumor control, which warrants further investigation into this matter. The available evidence suggests that in patients with 1 to 2 brain metastases, both SRS alone and SRS with WBRT offer equivalent levels of survival when compared with patients treated with surgery with WBRT. Research has been conducted that reports a survival advantage in patients with 1 to 3 brain metastases that were treated with SRS with WBRT.

CONCLUSIONS

SRS can be an advantageous course of treatment in specific patient groups when utilized alone, after surgery, with WBRT, or in combination with either or both of the treatment modalities. Although treatment approaches have been refined, many questions remain unanswered and further clinical evidence is needed to guide physicians in their future treatment decisions regarding treating patients in specific clinical scenarios.

Timing and risk factors for new brain metastasis formation in patients initially treated only with Gamma Knife surgery

Object

Stereotactic radiosurgery has been shown to afford a reasonable chance of local tumor control. However, new brain metastasis can arise following successful local tumor control from radiosurgery. This study evaluates the timing, number, and risk factors for development of subsequent new brain metastasis in a group of patients treated with stereotactic radiosurgery alone.

Methods

One hundred seventeen patients with histologically confirmed metastatic cancer underwent Gamma Knife surgery (GKS) to treat all brain metastases demonstrable on MR imaging. Patients were followed clinically and radiologically at approximately 3-month intervals for a median of 14.4 months (range 0.37–51.8 months). Follow-up MR images were evaluated for evidence of new brain metastasis formation. Statistical analyses were performed to determine the timing, number, and risk factors for development of new brain metastases.

Results

The median time to development of a new brain metastasis was 8.8 months. Patients with 3 or more metastases at the time of initial radiosurgery or those with cancer histologies other than non–small cell lung carcinoma were found to be at increased risk for early formation of new brain metastasis (p < 0.05). The mean number of new metastases per patient was 1.6 (range 0–11). Those with a higher Karnofsky Performance Scale score at the time of initial GKS were significantly more likely to develop a greater number of brain metastases by the last follow-up evaluation.

Conclusions

The timing and number of new brain metastases developing in patients treated with GKS alone is not inconsequential. Those with 3 or more metastases at the time of radiosurgery and those with cancer histology other than non–small cell lung carcinoma were at greater risk of early formation of new brain metastasis. Frequent follow-up evaluations, such as at 3-month intervals, appears appropriate in this patient population, particularly in high-risk patients. When detected early, salvage treatments including repeat radiosurgery can be used to treat new brain metastasis.

Brain metastases from solid tumors: disease outcome according to type of treatment and therapeutic resources of the treating center

Background

To evaluate the therapeutic strategies commonly employed in the clinic for the management of brain metastases (BMs) and to correlate disease outcome with type of treatment and therapeutic resources available at the treating center.

Methods

Four Cancer centres participated to the survey. Data were collected through a questionnaire filled in by one physician for each centre.

Results

Clinical data regarding 290 cancer patients with BMs from solid tumors were collected. Median age was 59 and 59% of patients had ≤ 3 brain metastases. A local approach (surgery and stereotactic radiosurgery) was adopted in 31% of patients. The local approach demonstrated to be superior in terms of survival compared to the regional/systemic approach (whole brain radiotherapy and chemotherapy, p = <.0001 for survival at 2 years). In the multivariate analysis local treatment was an independent prognostic factor for survival. When patients were divided into 2 groups whether they were treated in centers where local approaches were available or not (group A vs group B respectively, 58% of patients with ≤ 3 BMs in both cohorts), more patients in group A received local strategies although no difference in time to brain progression at 1 year was observed between the two groups of patients.

Conclusions

In clinical practice, local strategies should be integrated in the management of brain metastases. Proper selection of patients who are candidate to local treatments is of crucial importance.

Cognitive Sparing during the Administration of Whole Brain Radiotherapy and Prophylactic Cranial Irradiation: Current Concepts and Approaches

Whole brain radiotherapy (WBRT) for the palliation of metastases, or as prophylaxis to prevent intracranial metastases, can be associated with subacute and late decline in memory and other cognitive functions. Moreover, these changes are often increased in both frequency and severity when cranial irradiation is combined with the use of systemic or intrathecal chemotherapy. Approaches to preventing or reducing this toxicity include the use of stereotactic radiosurgery (SRS) instead of WBRT; dose reduction for PCI; exclusion of the limbic circuit, hippocampal formation, and/or neural stem cell regions of the brain during radiotherapy; avoidance of intrathecal and/or systemic chemotherapy during radiotherapy; the use of high-dose, systemic chemotherapy in lieu of WBRT. This review discusses these concepts in detail as well as providing both neuroanatomic and radiobiologic background relevant to these issues.

The role of stereotactic radiosurgery in the management of patients with newly diagnosed brain metastases: a systematic review and evidence-based clinical practice guideline

QUESTION

Should patients with newly-diagnosed metastatic brain tumors undergo stereotactic radiosurgery (SRS) compared with other treatment modalities? Target population These recommendations apply to adults with newly diagnosed solid brain metastases amenable to SRS; lesions amenable to SRS are typically defined as measuring less than 3 cm in maximum diameter and producing minimal (less than 1 cm of midline shift) mass effect. Recommendations SRS plus WBRT vs. WBRT alone Level 1 Single-dose SRS along with WBRT leads to significantly longer patient survival compared with WBRT alone for patients with single metastatic brain tumors who have a KPS > or = 70.Level 1 Single-dose SRS along with WBRT is superior in terms of local tumor control and maintaining functional status when compared to WBRT alone for patients with 1-4 metastatic brain tumors who have a KPS > or =70.Level 2 Single-dose SRS along with WBRT may lead to significantly longer patient survival than WBRT alone for patients with 2-3 metastatic brain tumors.Level 3 There is class III evidence demonstrating that single-dose SRS along with WBRT is superior to WBRT alone for improving patient survival for patients with single or multiple brain metastases and a KPS<70 [corrected].Level 4 There is class III evidence demonstrating that single-dose SRS along with WBRT is superior to WBRT alone for improving patient survival for patients with single or multiple brain metastases and a KPS < 70. SRS plus WBRT vs. SRS alone Level 2 Single-dose SRS alone may provide an equivalent survival advantage for patients with brain metastases compared with WBRT + single-dose SRS. There is conflicting class I and II evidence regarding the risk of both local and distant recurrence when SRS is used in isolation, and class I evidence demonstrates a lower risk of distant recurrence with WBRT; thus, regular careful surveillance is warranted for patients treated with SRS alone in order to provide early identification of local and distant recurrences so that salvage therapy can be initiated at the soonest possible time. Surgical Resection plus WBRT vs. SRS +/- WBRT Level 2 Surgical resection plus WBRT, vs. SRS plus WBRT, both represent effective treatment strategies, resulting in relatively equal survival rates. SRS has not been assessed from an evidence-based standpoint for larger lesions (>3 cm) or for those causing significant mass effect (>1 cm midline shift). Level 3: Underpowered class I evidence along with the preponderance of conflicting class II evidence suggests that SRS alone may provide equivalent functional and survival outcomes compared with resection + WBRT for patients with single brain metastases, so long as ready detection of distant site failure and salvage SRS are possible. SRS alone vs. WBRT alone Level 3 While both single-dose SRS and WBRT are effective for treating patients with brain metastases, single-dose SRS alone appears to be superior to WBRT alone for patients with up to three metastatic brain tumors in terms of patient survival advantage.

Relationship between volume, dose and local control in stereotactic radiosurgery of brain metastasis

The aim of this study is to analyse the efficacy of linear accelerator stereotactic radiosurgery (SRS) on prognostic factors, local control rate and survival in patients with brain metastasis. Patients with either a single metastasis or up to 4 multiple brain metastases with a maximum tumour diameter of 40 mm for each tumour and a Karnofsky Performance Status (KPS) > or = 70 were eligible for SRS. SRS was applied to 150 lesions in 86 consecutive patients with a median age of 60 years (median 1 and mean 1.7 lesions per patient, mean KPS 86). Median overall survival was 6.2 months after SRS and 9.7 months from diagnosis of brain metastasis. Multivariate analysis revealed that a KPS of 90 or more (p = 0.009) and female sex (p = 0.003) were associated with a longer survival. Radiation dose < or = 15 Gy (p = 0.017) and KPS < 90 (p = 0.013) were independent predictors of a shorter time to local failure. Five patients showed evidence of radionecrosis with a median survival of 14.8 months. Addition of WBRT neither led to improvement of survival nor to improvement of local control. Improved local control following SRS for brain metastases was associated with KPS > or =90, a radiation dose > 15 Gy and a PTV < 13 cc. The potential of hypofractionated stereotactic radiotherapy (SRT) for brain metastases of larger volume warrants further study.

Treatment of spinal tumors using cyberknife fractionated stereotactic radiosurgery: pain and quality-of-life assessment after treatment in 200 patients

OBJECTIVE

Benign and malignant tumors of the spine significantly impair the function and quality of life of many patients. Standard treatment options, including conventional radiotherapy and surgery, are often limited by anatomic constraints and previous treatment. Image-guided stereotactic radiosurgery using the CyberKnife system (Accuray, Inc., Sunnyvale, CA) is a novel approach in the multidisciplinary management of spinal tumors. The aim of this study was to evaluate the effects of CyberKnife stereotactic radiosurgery on pain and quality-of-life outcomes of patients with spinal tumors.

METHODS

We conducted a prospective study of 200 patients with benign or malignant spinal tumors treated at Georgetown University Hospital between March 2002 and September 2006. Patients were treated by means of multisession stereotactic radiosurgery using the CyberKnife as initial treatment, postoperative treatment, or retreatment. Pain scores were assessed by the Visual Analog Scale, quality of life was assessed by the SF-12 survey, and neurological examinations were conducted after treatment.

RESULTS

Mean pain scores decreased significantly from 40.1 to 28.6 after treatment (P < 0.001) and continued to decrease over the entire 4-year follow-up period (P < 0.05). SF-12 Physical Component scores demonstrated no significant change throughout the follow-up period. Mental Component scores were significantly higher after treatment (P < 0.01), representing a quality-of-life improvement. Early side effects of radiosurgery were mild and self-limited, and no late radiation toxicity was observed.

CONCLUSION

CyberKnife stereotactic radiosurgery is a safe and effective modality in the treatment of patients with spinal tumors. CyberKnife offers durable pain relief and maintenance of quality of life with a very favorable side effect profile.

Radiological progression of cerebral metastases after radiosurgery: assessment of perfusion MRI for differentiating between necrosis and recurrence

To assess the capability of perfusion MRI to differentiate between necrosis and tumor recurrence in patients showing radiological progression of cerebral metastases treated with stereotactic radiosurgery (SRS). From 2004 to 2006 dynamic susceptibility-weighted contrast-enhanced perfusion MRI scans were performed on patients with cerebral metastasis showing radiological progression after SRS during follow-up. Several perfusion MRI characteristics were examined: a subjective visual score of the relative cerebral blood volume (rCBV) map and quantitative rCBV measurements of the contrast-enhanced areas of maximal perfusion. For a total of 34 lesions in 31 patients a perfusion MRI was performed. Diagnoses were based on histology, definite radiological decrease or a combination of radiological and clinical follow-up. The diagnosis of tumor recurrence was obtained in 20 of 34 lesions, and tumor necrosis in 14 of 34. Regression analyses for all measures proved statistically significant (χ² = 11.6–21.6, P < 0.001–0.0001). Visual inspection of the rCBV map yielded a sensitivity and specificity of 70.0 respectively 92.9%. The optimal cutoff point for maximal tumor rCBV relative to white matter was 2.00 (improving the sensibility to 85.0%) and 1.85 relative to grey matter (GM), improving the specificity to 100%, with a corresponding sensitivity of 70.0%. Perfusion MRI seems to be a useful tool in the differentiation of necrosis and tumor recurrence after SRS. For the patients displaying a rCBV-GM greater than 1.85, the diagnosis of necrosis was excluded. Salvage treatment can be initiated for these patients in an attempt to prolong survival.

Outcomes and cost-effectiveness of gamma knife radiosurgery and whole brain radiotherapy for multiple metastatic brain tumors

We aimed to analyze the outcomes and cost-effectiveness of gamma knife radiosurgery (GKRS) and whole brain radiotherapy (WBRT) for multiple metastatic brain tumors. Over a period of 5 years, 156 patients with multiple metastatic brain tumors were enrolled and freely assigned by the referring doctors to either gamma knife radiosurgery (GKRS, Group A, n=56), or to whole brain radiotherapy (WBRT, Group B, n=100). The follow-up time was set at 1200 days (3.3 years) post-treatment. The number of tumors, patient age, extent of systemic disease and Karnofsky performance scale (KPS) score, were recorded and recursive partitioning analysis used. The outcomes analyzed were: mortality, survival time, neurological complications, post-treatment KPS score, quality-adjusted life years (QALY), and cost-effectiveness. A paired t-test was used for statistical analysis. Mortality rates for patients receiving GKRS and WBRT were 81.1% and 93.0%, respectively (p=0.05). The mortality rate was lower for GKRS (74.4%) than for WBRT (97.1%) in patients with initial KPS70 (p=0.02). The mortality rate was also significantly lower for GKRS (78.9%) than WBRT (95.5%) in patients with 2-5 tumors (p<0.05). Post-treatment KPS score (mean+/-standard deviation [s.d.] was higher for patients receiving GKRS (73.8+/-13.2) than for those receiving WBRT (45.5+/-26.0), p<0.01. The median survival time for GKRS and WBRT was 9.5 months and 8.3 months, respectively, p=0.72. The mean (+/- s.d.) QALY was 0.76+/-0.23 for GKRS and 0.59+/-0.18 for WBRT, respectively (p<0.05). The cost-effectiveness per unit of QALY was better for the GKRS treatment (US$10,381/QALY) than in the WBRT treatment (US$17,622/QALY), p<0.05. The cost-effectiveness per KPS score was also higher for the GKRS treatment (US$139/KPS score) than for WBRT (US$229/KPS score), p<0.01. Thus, the mortality rate for multiple metastatic brain tumors treated by GKRS is significantly better with a good initial KPS score and when the tumor number is 2-5. GKRS results in a better post-treatment KPS score, QALY, and higher cost-effectiveness than WBRT for treating multiple metastatic brain tumors.

Tumor bed radiosurgery after resection of cerebral metastases

OBJECTIVE

Adjuvant irradiation after resection of brain metastases reduces the risk of local recurrence. Whole-brain radiation therapy can be associated with significant neurotoxicity in long-term survivors of brain metastases. This retrospective study evaluates the role of tumor bed stereotactic radiosurgery as an alternative method of irradiation after initial resection of brain metastases to prevent local recurrence.

METHODS

Forty patients underwent tumor bed radiosurgery after resection of brain metastases at two separate academic medical centers. The median age was 59.5 years. Twenty patients (67.5%) had single metastases. Resection was complete in 80% and partial in 20% of the patients. At the time of radiosurgery, systemic disease was active in 57.5%, inactive in 32.5%, and in remission in 10% of the patients. The median Karnofsky Performance Scale score was 80% (range, 60-100%). Radiosurgery was performed a median of 4 weeks after tumor resection. The median cavity radiosurgery volume was 9.1 ml (range, 0.6-39.9 ml). The median margin and maximum radiation dose were 16 and 32 Gy, respectively.

RESULTS

Local control at the resection site was achieved in 73% of patients at a median follow-up period of 13 months. No variable significantly affected local control. New remote brain metastases occurred in 54% of the patients. Symptomatic radiation effect was seen in 5.4% of the patients. The median survival was 13 months after radiosurgery (range, 2-56 mo).

CONCLUSION

Tumor bed radiosurgery provides effective local control of the tumor after resection in most patients. These preliminary data support radiosurgery after resection rather than traditional radiation therapy.

Combined surgical resection and stereotactic radiosurgery for treatment of cerebral metastases

BACKGROUND

Patients with limited intracranial metastatic disease traditionally have been treated with surgery followed by WBRT. However, there is growing concern for the debilitating cognitive effects after WBRT in long-term survivors. We present a series of patients treated with surgery followed by SRS, while reserving WBRT as a salvage therapy for disease progression.

METHODS

Medical records from 15 patients with 1 to 2 cerebral metastases who underwent both resection and SRS were reviewed. Outcome measures included overall survival, survival by RPA class, EOR, local tumor control, progression of intracranial disease, need for WBRT salvage therapy, and COD.

RESULTS

Fifteen patients with cerebral metastases were treated with the combined surgery-SRS paradigm. Eight of the 15 patients (53.3%) were designated RPA class 1, with 6 of 15 (40.0%) in class 2 and 1 of 15 (6.7%) in class 3. Gross total resection was achieved in 12 cases (80.0%). Overall median survival was 20.0 months, with values of 22.0 and 13.0 months for RPA classes 1 and 2, respectively. Local recurrence occurred in 16.7% of those patients with GTR. Six patients (40.0%) went on to receive WBRT at a median of 8.0 months from initial presentation. Twelve patients (80.0%) had died at the completion of the study, and the COD was CNS progression in 33.3%.

CONCLUSIONS

Surgical resection combined with SRS is an effective treatment for selected patients with limited cerebral metastatic disease. Survival using this combined treatment was equivalent to or greater than that reported by other studies using surgery + WBRT or SRS + WBRT.

Multidisciplinary management of brain metastases

Metastatic brain tumors are the most common intracranial neoplasms in adults. The incidence of brain metastases appears to be rising as a result of superior imaging modalities, earlier detection, and more effective treatment of systemic disease. Therapeutic approaches to brain metastases include surgery, whole brain radiotherapy (WBRT), stereotactic radiosurgery (SRS), and chemotherapy. Treatment decisions must take into account clinical prognostic factors in order to maximize survival and neurologic function whilst avoiding unnecessary treatments. The goal of this article is to review important prognostic factors that may guide treatment selection, discuss the roles of surgery, radiation, and chemotherapy in the treatment of patients with brain metastases, and present new directions in brain metastasis therapy under active investigation. In the future, patients will benefit from a multidisciplinary approach focused on the integration of surgical, radiation, and chemotherapeutic options with the goal of prolonging survival, preserving neurologic and neurocognitive function, and maximizing quality of life.

Treatment of central nervous system metastases: parenchymal, epidural, and leptomeningeal

PURPOSE OF REVIEW

With prolonged survival from systemic therapies in the adjuvant and salvage setting, and because these agents cannot cross the intact blood-brain barrier, central nervous system metastases are becoming a therapeutic challenge in oncology.

RECENT FINDINGS

Recent therapeutic achievements include an extended use of surgery and radiosurgery. Although each of these treatment modalities has its own indications, in patients eligible for both treatments the upfront comparison of these two techniques has not been performed yet. Systemic chemotherapies and biotherapies may be effective in the management of central nervous system metastases as they may act on both neurologic and extra-central nervous system lesions. In the treatment of epidural metastases, a surgical procedure providing immediate direct circumferential decompression of the spinal cord followed by local irradiation has been demonstrated in a prospective randomized trial. The management of leptomeningeal metastases remains controversial and of limited efficacy especially in chemoresistant tumours and still relies on the combination of chemotherapy (intrathecal and intravenous) and focal radiotherapy.

SUMMARY

Aggressive treatments in patients with early diagnosis and in whom central nervous system metastases are the life-threatening location may provide a substantial increase in survival and favourably affect quality of life.

Distribution of Brain Metastases in Relation to the Hippocampus: Implications for Neurocognitive Functional Preservation

PURPOSE

With the advent of intensity-modulated radiotherapy, the ability to limit the radiation dose to normal tissue offers an avenue to limit side effects. This study attempted to delineate the distribution of brain metastases with relation to the hippocampus for the purpose of exploring the viability of tomotherapy-guided hippocampal sparing therapy potentially to reduce neurocognitive deficits from radiation.

METHODS AND MATERIALS

The pre-radiotherapy T1-weighted, postcontrast axial MR images of 100 patients who received whole brain radiotherapy, stereotactic radiosurgery, or a radiosurgical boost following whole brain radiotherapy between 2002 and 2006 were examined. We contoured brain metastases as well as hippocampi with 5-, 10-, and 15-mm expansion envelopes.

RESULTS

Of the 272 identified metastases, 3.3% (n = 9) were within 5 mm of the hippocampus, and 86.4% of metastases were greater than 15 mm from the hippocampus (n = 235). The most common location for metastatic disease was the frontal lobe (31.6%, n = 86). This was followed by the cerebellum (24.3%, n = 66), parietal lobe (16.9%, n = 46), temporal lobe (12.9%, n = 35), occipital lobe (7.7%, n = 21), deep brain nuclei (4.0%, n = 11), and brainstem (2.6%, n = 7).

CONCLUSIONS

Of the 100 patients, 8 had metastases within 5 mm of the hippocampus. Hence, a 5-mm margin around the hippocampus for conformal avoidance whole brain radiotherapy represents an acceptable risk, especially because these patients in the absence of any other intracranial disease could be salvaged using stereotactic radiosurgery. Moreover, we developed a hippocampal sparing tomotherapy plan as proof of principle to verify the feasibility of this therapy in the setting of brain metastases.

Evolving management of newly diagnosed brain metastases: expanding role of radiosurgery in lieu of whole brain radiation

The use of stereotactic radiosurgery has grown increasingly prevalent in the management of patients with brain metastases. In this perspective we contend that a large number of patients can be offered the alternative of treatment with this modality alone, reserving whole brain radiation for salvage. The relevant data will be presented supporting this approach, with emphasis on the toxicities of whole brain radiation and equivalence of survival outcomes regardless of treatment approach. Patient selection for radiosurgery alone will also be addressed.

Radiobiology of brain metastasis: applications in stereotactic radiosurgery

Stereotactic radiosurgery is a neurosurgical modality in which a target lesion can be irradiated while sparing normal brain tissue. In some respects, brain metastasis is well suited for radiosurgery, as metastatic lesions tend to be small and well circumscribed and displace (but do not infiltrate) normal brain tissue, facilitating the delivery of radiation. Advances in stereotactic radiosurgical planning, such as blocking patterns and beam shaping, have allowed further targeting of discrete lesions while minimizing the effect of radiation toxicity on the central nervous system. In this paper the authors review the radiobiology of brain metastases and stereotactic radiosurgical approaches that can be used to treat these tumors safely.

Stereotactic Body Radiation Therapy (SBRT) for lung metastases

The curative treatment of oligometastases with radiotherapy remains an area of active investigation. We hypothesise that treating oligometastases with SBRT can prolong life and potentially cure patients, while in patients with multiple lung metastases SBRT can improve quality of life. Fifty patients with lung metastases were treated on this study. Individuals with five or fewer total lesions were treated with curative intent. Individuals with > five metastases were treated palliatively. Most patients (62%) received 5 Gy/fraction for a total of 50 Gy. The number of targets treated per patient ranged from one to five (mean 2.6). Tumor sizes ranged from 0.3-7.7 cm in maximal diameter (median 2.1 cm). Mean follow-up was 18.7 months. Local control of treated lesions was obtained in 42 of 49 evaluable patients (83%). Of the 125 total lesions treated, eight progressed after treatment (94% crude local control). The median overall survival time from time of treatment completion of the curatively treated patients was 23.4 months. The progression-free survival of the same group of patients was 25% and 16% at 12 and 24 months, respectively. Grade 1 toxicity occurred in 35% of all the patients, 6.1% had grade 2 toxicity, and 2% had grade 3 toxicity. Excellent local tumor control rates with low toxicity are seen with SBRT. Median survival time and progression-free survival both appear better than that achieved with standard care alone. Long-term progression-free survival can be seen in a subset of patients when all tumors are targeted.

Cerebral metastases—a therapeutic update

Cerebral metastases remain a common complication among patients with cancer. Historically, whole-brain radiotherapy has remained the standard of care, with surgery being reserved for selected cases. Recent advances have changed our practice, however. In particular, stereotactic radiosurgery has emerged as a vital treatment modality for this disease. In addition, chemotherapy, including temozolomide, topoisomerase inhibitors and antimetabolites, and treatment sensitizers, such as efaproxiral and motexafin gadolinium, are actively being assessed in clinical trials, and are likely to play an increasing role in the management of cerebral metastases in the future. Nonetheless, many uncertainties remain, such as the optimal combination and timing of therapeutics. As the arsenal of therapeutics expands, it will be increasingly important to select appropriate patients for a particular treatment paradigm. Understanding the efficacy and toxicity of treatment is essential to this task.

Gamma Knife surgery for metastatic brainstem tumors

Object

The authors review imaging and clinical outcomes in patients with metastatic brainstem tumors treated using Gamma Knife surgery (GKS).

Methods

Between March 1989 and March 2005, 53 patients (24 men and 29 women) with metastatic brainstem lesions underwent GKS. The metastatic deposits were located in the midbrain in eight patients, the pons in 42, and the medulla oblongata in three. Lung cancer was the most common primary malignancy, followed by breast cancer, melanoma, and renal cell carcinoma. The mean volume of the metastatic deposits at the time of treatment was 2.8 cm3 (range 0.05–21 cm3). The prescription doses varied from 9 to 25 Gy (mean 17.6 Gy).

Imaging follow-up studies were not completed in 16 patients, because of the short-term survival in 11 and patient refusal in five. Of the remaining 37 patients, who underwent an imaging follow-up evaluation at a mean of 9.8 months (range 1–25 months), the tumors disappeared in seven, shrank in 22, remained unchanged in three, and grew in five. All but one of 18 patients with asymptomatic brainstem deposits remained free of symptoms. In 35 patients with symptomatic brainstem deposits, neurological symptoms improved in 21, remained stable in 11, and worsened in three. At the time of this study, 10 patients were alive, and their survival ranged from 3 to 52 months after treatment. Thirty-four patients died of extracranial disease, three of the progressing metastatic brainstem lesion, and six of additional progressing intracranial deposits in other parts of the brain. The overall median survival period was 11 months after GKS. In terms of survival, the absence of active extracranial disease was the only favorable prognostic factor. Neither previous whole-brain radiation therapy nor a single brainstem metastasis was statistically related to the duration of survival.

Conclusions

Compared with allowing a metastatic brainstem lesion to take its natural course, GKS prolongs survival. The risks associated with such treatment are low. The severity of systemic diseases largely determines the prognosis of metastases to the brainstem.