Stereotactic Radiosurgery Can Improve Control of Brain Metastases

Rupesh Kotecha, MD

Brain metastases are a significant and growing healthcare burden. With the growth and aging of populations worldwide, the global cancer burden is expected to increase to nearly 22 million by 2030, at which time cancer will be the leading cause of death in the United States.^1,2 Large-scale studies of brain metastases are lacking, but reported percentages of patients with systemic disease who develop brain metastases range from 9% to 50%.³ The cost of treating brain metastases is also rising. The growth in the incidence and cost of treating brain metastases creates a critical challenge for physicians and cancer care centers: how to optimize and ensure access to high-quality care to improve patient quality of life and survival while simultaneously implementing cost-effective clinical workflows and processes.

Stereotactic Radiosurgery Improves Brain Metastasis Treatment

Recent advances in the delivery of technology and treatment regimens for stereotactic radiosurgery (SRS) enable new approaches to improve patient outcomes and clinical efficiency. These technology advances are enabling new precision radiation medicine regimens that have been shown to improve local tumor control rates with minimal toxicity. Key to the success of treating brain metastases with SRS is using a regimen tailored to the size of the lesion and individual patient need.

Table. Miami Cancer Institute Brain Metastases SRS Guidelines⁴

As shown in the Table⁴, SRS is currently being used in single-session, hypofractionated, and multisession (staged) regimens, depending on the clinical scenario. Single-session regimens can be used to treat lesions up to 3 cm in diameter and offer patients the greatest convenience. Hypofractionated regimens are the most versatile and can be used across the greatest range of lesion size. Although lesions greater than 3 cm are usually treated with multisession SRS administered over several weeks, Miami Cancer Institute in Kendall, Florida, has successfully used hypofractionated regimens in these cases for improved patient convenience. Regardless of regimen, dose reduction is performed for lesions in specific locations, such as those in the brainstem or in proximity to the optic pathway.

SRS: Cost-Efficient and Clinically Effective

Noninvasive SRS methods offer a cost-efficient and clinically effective treatment that can be used in addition to or as an alternative to intracranial surgery.⁵ SRS can also be readily incorporated into multimodal treatment regimens that may include surgery, chemotherapy, targeted therapy, or immunotherapy. SRS is flexible in terms of how and when it can be utilized, and this enables the development of highly personalized treatment regimens based on the stage of the patient’s disease, the histology of the tumor, and even the molecular profile of the tumor. Importantly, the availability of a radiation delivery system that can be used for single-treatment, hypofractionated, and staged radiation therapy regimens, such as Gamma Knife, allows cancer centers to optimize SRS treatment plans to best meet each patient’s needs while streamlining clinical workflows and maximizing the value of their device investment.

Rationale for Implementing SRS

In July 2017, Miami Cancer Institute established a dedicated SRS clinic to facilitate access to this important therapeutic option and to effectively integrate SRS into its clinical workflows for treating brain metastases. The decision to establish the SRS clinic was based on 4 key factors. First, a growing body of data supports the clinical benefits of SRS in treating brain metastases. Second, SRS offers clinicians the opportunity to provide patients with precision radiation medicine regimens that are well tolerated and can provide durable local tumor control. Third, the availability of an SRS system that could be used to provide single-session, hypofractionated, and staged SRS regimens enabled the center to purchase a single device that could be used to treat all patients undergoing SRS, offering a greater return on its investment in technology. Finally, the establishment of the dedicated SRS clinical team helped to differentiate Miami Cancer Institute from other cancer centers in the region, allowing it to attract more patients and recruit staff members who want to be on the cutting edge of cancer therapy.

Once the decision to establish the SRS clinic was made, Miami Cancer Institute developed a variety of processes and procedures designed to optimize the use and outcomes of SRS in the treatment of brain metastases. Critical to the success of the program was implementing processes to ensure effective integration and coordination among neurologists, radiation oncologists, and medical oncologists for patients receiving complex, multimodal care. This included establishing a weekly meeting of a multidisciplinary team. This team helped to ensure effective coordination with medical oncology with respect to the timing of systemic therapy (targeted therapy or immunotherapy) relative to other treatments, including SRS, and to reduce delays in initiating or continuing cytotoxic chemotherapy by timing SRS around optimized chemotherapy cycles.

In addition to facilitating coordination and data sharing among its care providers, it is also important to establish SRS clinical workflows that streamline and optimize the patient journey while increasing patient volume and supporting cost-effective operations. Key to achieving this is implementing multidisciplinary treatment guidelines and care paths that ensure appropriate evidence-based treatment. The multidisciplinary guideline that Miami Cancer Institute developed and implemented to determine if a metastatic lesion is eligible for SRS treatment is shown in Figure 1.

Another important factor in successfully integrating SRS into the brain metastasis treatment paradigm is ensuring that every patient with a brain tumor or brain metastasis undergoes a planning magnetic resonance imaging (MRI) at the time of imaging. This is done to facilitate the downstream workflow for those patients who will, in fact, undergo SRS. Gamma Knife MRI sequences are used rather than diagnostic sequences because the former can be used for target volume delineation for radiation treatments, not just for SRS. This approach streamlines downstream clinical workflow for SRS patients and allows a more rapid response if the patient develops a new metastatic lesion.

Figure 1. Miami Cancer Institute's Multidisciplinary Treatment Guideline

Figure 2. Form Used for Triaging Patients to the SRS Workflow at Miami Cancer Institute

To ensure that all patients who could potentially benefit from SRS are appropriately evaluated, the medical oncology, neurology, radiation oncology, and neuro-oncology departments can all triage directly to the SRS workflow. Additionally, the use of a standard form for all patients with brain metastases (Figure 2) helps to simplify and facilitate scheduling of pretreatment scans, SRS mask customization, and other care.

Initial SRS Clinic Experience

More than 700 metastatic lesions have been treated with SRS since the establishment of the SRS clinic in July 2017, demonstrating that a coordinated, integrated approach can increase utilization of this important form of radiation therapy. A key to this success was the support and commitment of clinicians across multiple departments, as evidenced by a 98% physician attendance rate at the weekly multidisciplinary meeting in 2018 and a 100% attendance rate thus far in 2019. Effective integration of SRS into the brain metastasis care path has allowed 20 patients to date to receive same-day service and immediate treatment for new brain metastases. The ability to treat these patients with SRS within 24 hours of new lesion detection eliminated delays for initiating systemic therapy and costs for additional MRI while reducing patient anxiety.

Delays in initiating SRS can decrease both clinical efficacy and clinical efficiency. A recent study found that 41% of patients require a change in management if the planning MRI is performed within 7 days of initiating SRS and that 78% require a change in management if SRS is initiated more than 7 days after the planning MRI.6 With an integrated and defined process for triaging patients to the SRS care path and tight coordination between diagnostic imaging and SRS, the median time between the planning MRI and initiation of SRS treatment at Miami Cancer Institute is only 2 days. Similarly, close coordination between the neurosurgery and radiation oncology departments has increased the proportion of patients with radiation oncology/neurology dual SRS plans from 44% to 78%. This again helps to reduce treatment delays and improve clinical efficiency.

The establishment of the dedicated SRS clinic has been so successful that Miami Cancer Institute has created a multidisciplinary annual symposium in order to build awareness of the program within the regional medical community and to support other care centers seeking to integrate SRS into their brain metastasis treatment paradigms.

Conclusions

SRS is a flexible and effective tool for developing precision radiation medicine regimens to treat brain metastases. Importantly, evolving SRS treatment regimens can improve local tumor control and survival, even for patients with large and complex metastases not previously considered amenable to radiation therapy. Realizing the potential of SRS to improve the care and outcomes for patients with brain metastases requires a dedicated and multidisciplinary approach that utilizes evidence-based medicine to evaluate and triage these patients to the regimen most likely to provide clinical benefit.

References

1. Global Cancer Facts & Figures 3rd Edition. American Cancer Society website. cancer.org/research/cancer-facts-statistics/global. html. Published 2015. Accessed September 4, 2019.
2. American Society of Clinical Oncology. The state of cancer care in America, 2014: a report by the American Society of Clinical Oncology. J Oncol Pract. 2014;10(2):119-142. doi: 10.1200/ JOP.2014.001386.
3. Cagney DN, Martin AM, Catalano PJ, et al. Incidence and prognosis of patients with brain metastases at diagnosis of systemic malignancy: a population-based study. Neuro Oncol. 2017;19(11):1511-1521. doi: 10.1093/neuonc/nox077.
4. Lal LS, Byfield SD, Chang EL, et al. Cost-effectiveness analysis of a randomized study comparing radiosurgery with radiosurgery and whole brain radiation therapy in patients with 1 to 3 brain metastases. Am J Clin Oncol. 2012;35(1):45-50. doi: 10.1097/ COC.0b013e3182005a8f.
5. Salkeld AL, Hau EKC, Nahar N, et al. Changes in brain metastasis during radiosurgical planning. Int J Rad Oncol Biol Phys. 2018;102(4):727-733. doi: 10.1016/j.ijrobp.2018.06.021.
6. Kotecha R, Mehta MP. The complexity of managing large brain metastasis. Int J Radiat Oncol Biol Phys. 2019;104(3):483-484. doi: 10.1016/j.ijrobp.2018.02.160.