Surgery: Current Research

Brain Metastases from Breast Cancer Treated with Neurosurgery

Paulo Roriz^{* *}Correspondence: Paulo Roriz, Editorial Office, Surgery: Current Research, Belgium, Email:

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Introduction

The most prevalent cancer in women worldwide is breast cancer, and a recent database assessment revealed that 20% to 30% of breast cancer patients have metastasis as their primary cause of death. Brain metastases affect 10% to 16% of individuals with metastatic breast cancer, and this number is rising as more patients are surviving longer after a first diagnosis. Because of advancing systemic disease or uncontrolled neurological disease, the majority of patients with brain metastases have shorter lifetimes.

After a relapse in the central nervous system, women with breast cancer had a median survival time of 5 months to 14 months. Extracranial lesions are now more manageable thanks to recent developments in adjuvant therapies like anti-human epidermal growth factor receptor-2 (anti-HER-2) monoclonal antibody, increasing the likelihood that brain metastasis is the first site of recurrence and that effective treatment of brain metastasis will result in longer survival. Corticosteroids, surgery, radiosurgery or radiotherapy, chemotherapy, and immunotherapy are all used to treat brain metastases. With improvements in supporting neurosurgical techniques and technologies, surgical treatment of brain metastases has advanced dramatically. Discussing the traits and surgical management of metastatic brain tumors from breast cancer is the main goal of this review.

Characteristics of metastatic brain tumors of breast cancer

Imaging techniques are required to find and distinguish brain neoplasms from other benign lesions. Because the blood-brain barrier has been damaged, intracranial metastases frequently exhibit enhancement with a contrast agent. Hematogenous spread causes metastatic lesions to typically manifest as cortical or subcortical lesions, which frequently begin as smaller, solidly enhancing lesions before necrosis causes them to ringenhance. Breast, colon, renal cell, and thyroid cancers are among the prevalent cancers that frequently generate a single brain metastasis; however, lung cancer and melanoma are more likely to do so. Numerous pathologies, such as metastatic illness, lymphoma, sarcoid, vasculitis like Bechet’s disease, demyelinating disorders, and bacterial or fungal infections can all exhibit nodular solid amplification. High-grade glioma, on the other hand, is the most frequent cause of ring-enhanced lesions 40% and is followed by metastases 30%, abscesses 8%, and demyelinating illness 6%. Standard MRI sequences like T2-weighted imaging, diffusion-weighted imaging, and contrast-enhanced T1-weighted imaging can differentiate between metastases and other clinical diseases, but it is still difficult to tell a single metastasis apart from a glioblastoma. It examined the neuroimaging characteristics of metastatic brain tumors and discovered that relative cerebral blood volumes and magnetic resonance spectroscopies appear to be useful in distinguishing metastases from glioblastomas. Although very few studies have examined the connections between MRI characteristics and tumor histology, MRI is one of the most reliable techniques for evaluating metastatic brain cancers. For sub classification, it was evaluated that the MRI features of brain metastases from several subtypes of recurrent breast cancer. All MRI tests were carried out using a 1.5-Tesla MRI scanner, and the patients in that study were classified as having a luminal type, HER-2-enriched type, or triple-negative breast tumors. While the majority of patients with triple-negative breast cancers displayed distinguishing characteristics of cystic and necrotic lesions, both patients with luminal type malignancies and those with HER-2 enriched type cancers displayed solid tumors with or without perifocal edoema. It is common for brain metastatic lesions to have histological and genetic differences from the source tumor, suggesting that MRI is a useful technique for examining the tumor type of brain metastasis.

When removing brain tumors, the possibility of tumor invasion into the tissues of the central nervous system should be taken into account. Surgery is required to completely remove glioblastoma, one of the primary central nervous system tumors because malignant cells can invade nearby tissue far beyond the tumor's core. Metastatic brain tumors, in contrast, are less intrusive. Breast cancer invades the tissue up to 1 mm from the tumor core. Therefore, by resecting the tumor with an additional margin from the tumor border, breast cancers can be completely eradicated.

Surgical strategy for metastatic brain tumors

The best surgical outcome for treating metastatic brain tumors is known as Gross Total Resection (GTR). The Congress of Neurological Surgeons most recent recommendations favor GTR over subtotal resection to increase overall survival and lengthen the time until recurrence. However, even following treatment with GTR followed by SRS, recurrence affects 20% of individuals.

Metastatic brain tumors are typically well-defined masses encircled by gliotic tissue as opposed to diffusely infiltrating tumors like gliomas. According to some reports, conventional GTR did not provide the same level of local control as supramarginal resection, which was accomplished by removing an extra 5 mm of surrounding tissue from the tumor border. In many situations, supramarginal resection can be accomplished with awake surgery, even for brain metastases in eloquent areas. However, even with intraoperative neurophysiological monitoring or awake surgery, supramarginal excision cannot prevent transient impairments like supplementary motor area syndrome. It is therefore essential for both surgeons and patients to plan carefully for a maximally safe excision with a minimum amount of tissue stress. Typically, tumor resection is carried out either en bloc or piecemeal. Debulking the mass and then removing the capsule are the standard steps in piecemeal resection. This method can achieve GTR, but there is a chance of local recurrence and diffusion. This assessed the prevalence of leptomeningeal disease following the removal of supra- and infratentorial metastases and discovered that only 5.7% of patients who had en bloc resection compared to 13.9% of patients who underwent piecemeal resection experienced this complication. En-bloc resection prevents exposure of the tumor to adjacent tissue by securely dissecting the tumor along the brain-tumor interface. However, the surgical management of tumors larger than 9.71 cm3 reduces the en bloc resection's recurrence-lowering efficacy. Additionally, in some circumstances, such as when tumors are attached to or invasive into eloquent areas, piecemeal excision is unavoidable. According to these data, when removing a single brain metastasis, enbloc tumor excision is essentially advised to reduce leptomeningeal illness.

Resection of cystic tumors

Breast cancer metastases to the brain that are cystic have a poor prognosis. Due to the increased danger of leptomeningeal spread, complete excision of the cyst wall is required during the surgical treatment of cystic tumors to achieve GTR. When a cyst is punctured to decompress a tumor after surgery, the cyst shrinks, blurring the line between the tumor and the surrounding brain tissue. Injection of pyoktanin blue solution diluted in 0.3% saline is a method for seeing the inner cyst wall. Although the risk of tumor diffusion after cyst puncture exists, solidification using fibrin glue may prevent it and make it simpler to separate the tumors from the surrounding brain tissue.

Supporting devices for safe GTR

Microscopic surgery: In contemporary neurosurgery, operative tools that allow for clear surgical field observation are crucial. A surgical microscope gives a clear view of the neurovascular microstructures, and these microscopes are commonly used in practically all cranial and spinal procedures around the world. The microscope can also be connected to other devices for image guidance. Patients with brain metastases may benefit from the use of fluorescein or neocyanine green with a special microscope filter to maximize the area of resection.

Neuronavigation: Over the past few decades, the use of an intraoperative frameless stereotactic navigation system, dubbed "neuronavigation," has emerged as a crucial tool for difficult operations, such as the surgical treatment of malignant tumors.

With the aid of a neuronavigation device, the surgeon can correlate the actual position of tumors with preoperative pictures from tests like functional MRI, computed tomography, positron emission tomography, and computed tomography. This makes it possible to identify the resection location and comprehend the architecture of the surgical target and surrounding brain tissue. Optical and electromagnetic neuronavigation are two different methods of neuronavigation. Various metal instruments can be used during surgery thanks to the optical system. However, electromagnetic neuronavigation has the benefit of doing away with the optical line-ofsight issue. When doing endoscopic surgery for seller lesions and ventricular lesions, electromagnetic neuron avigation's value is very clear. Both types of neuronavigation have comparable and excellent accuracy. The precision of surgical guiding is decreased by brain shift, which is one drawback of using a navigation system. Gravity, the shifting of surrounding brain tissue back into the resection space, and cerebrospinal fluid leakage when the dura mater is removed are the causes of brain shift. Because there was no one measurement method for detecting brain shift, the maximal brain shift ranged widely from 2.3 mm to 30.9 mm.

Neurophysiological monitoring: Predicting and preventing surgical neurological impairments requires the use of intraoperative neurophysiological monitoring. In the context of glioma surgery, efficient intraoperative mapping and monitoring approaches have emerged. Intraoperative monitoring is used to safely remove the maximum amount of tumor by accurately locating cortical regions and subcortical circuits, including those involved in motor, sensory, linguistic, and cognitive functions. An equal level of resection in both eloquent and non-eloquent areas may be achieved with intraoperative monitoring, according to a prospective controlled trial. Recently, it was discovered that intraoperative motor system monitoring could lessen postoperative motor deficits when a metastatic brain tumor was surgically removed. To avoid local recurrence, supramarginal excision of metastatic brain tumors is preferred, along with extra removal of the surrounding brain tissue. Therefore, during tumor resection, intraoperative neurophysiological monitoring offers crucial functional information, particularly when the amount of resection approaches an expressive area.

 

Conclusion

Recent improvements in systemic treatment have led to a rise in the prevalence of brain metastases from breast cancer. The molecular subtypes of breast cancer can be estimated using neuroimaging of metastatic brain tumors, which then forecasts the tumor's aggressiveness. In patients with a small number of brain metastases and a generally satisfactory performance status, surgical excision remains to be crucial. In order to prevent leptomeningeal illness, en-bloc tumor excision is often advised. We anticipate that the rate of local control of brain metastases will significantly increase as a result of recent developments in supporting neurosurgical techniques and technologies. Thermotherapy, oncolytic virus therapy, and gene therapy have all been covered in a number of preclinical papers. Novel treatment approaches will become commonplace in the not-too-distant future.