Surgical Treatment of Brain Metastases
Abstract & Commentary
By William Cobb, MD, and Theodore H. Schwartz, MD, PhD. Dr. Cobb is Graduate Staff, New York Presbyterian Hospital/Weill Cornell Medical Center. Dr. Schwartz is Professor of Neurosurgery, Otolaryngology, Neurology and Neuroscience, Weill Cornell Medical College, New York Presbyterian Hospital. Dr. Cobb and Dr. Schwartz report no financial relationships relevant to this field of study.
Synopsis: Surgical removal of brain metastases remains an important part of palliative therapy for metastatic cancer.
Source: Rogne SG, et al. Craniotomy for brain metastases: A consecutive series of 316 patients. Acta Neurol Scand DOI:10.1111/j.1600-0404.2011.01590.x.
Brain metastases are the most common type of brain tumor; more than 100,000 people are diagnosed with metastatic brain tumors in the United States each year. Metastatic lesions are diagnosed in as many as one-third of cancer patients, which portends a poor prognosis in general. Overall median survival from the time of diagnosis is approximately 7 months, making metastatic brain tumors a significant health concern. Treatment usually consists of surgical resection followed by whole brain radiation therapy (WBRT), although stereotactic radiosurgery has recently become more frequent for initial upfront treatment and WBRT can sometimes be avoided in a subpopulation of patients.
In the article by Rogne et al, the authors investigated the role of craniotomy as the initial treatment for brain metastases, determined the overall survival and surgical mortality, and identified prognostic factors in this patient population. In their series, 316 patients from 2003 to 2009 underwent craniotomy for treatment of cerebral metastases at the Oslo University Hospital and its associates in Norway. Data on gender, age, number, location, histology, extent of disease, performance scores, and postoperative radiation treatment were collected for each patient and evaluated by uni- and multivariate analysis.
The authors found the annual incidence of craniotomy for treatment of brain metastases in Norway to be 2.6 craniotomies/100,000 inhabitants per year. Patients with primary melanoma and lung cancer had the highest likelihood of undergoing craniotomy while non-melanoma skin cancer, prostate cancer, and upper gastrointestinal cancer had the lowest. The mortality rate within 30 days of the procedure was 3.8%, half of which was directly related to surgery. Median overall survival of all patients was 9.2 months. Negative prognostic indicators included Karnofsky score < 7, age > 65, multiple lesions, metastases in eloquent areas, uncontrolled primary disease, and extracranial metastases. RPA classification, which is a composite of Karnofsky score, age, and extent of disease, was shown to be the most important prognostic indicator, in that median survival for RPA Class I, II, and III were 16.2, 8.9, and 5.6 months, respectively. In addition, postoperative whole brain radiation treatment was found to improve overall survival. Those factors that had no correlation to overall survival included histology, gender, supra- vs infratentorial location, and known primary.
These authors provide population-based data that reconfirm the findings of a myriad of other studies. There is little new information here. As cancer treatment evolves, it becomes more apparent that each patient must be treated as an individual based on the specific characteristics of his or her disease and that each treatment paradigm must be tailored accordingly. Poor performance score, older age, multiple lesions or tumors in eloquent areas, extent of systemic disease, and lack of radiation therapy portend a decreased survival, which is in agreement with the existing literature. Interestingly, the authors did not find a difference when analyzing survival based on histology of the metastatic brain tumor. This is surprising given the high degree in variation in the aggressiveness of different types of cancers and the response of different cancers to whole brain radiation. This may result from the small sample size of the study where some of the histological subtypes had fewer than 20 patients. A larger sample size might show a statistically significant difference in the overall survival between different histological types of metastatic brain tumors. One factor found to have a positive effect on overall survival was postoperative radiation therapy; however, not all of the patients received the same postoperative radiation treatment. Twenty-six of the 316 patients received radiation therapy other than WBRT alone and 46 received no radiation therapy at all. There is clearly a selection bias here, and the authors provide no explanation for why some patients received radiation therapy and others did not. Hence, this conclusion is suspect. Further studies will be needed to fully elucidate the benefits of WBRT in the treatment of metastatic brain tumors and which patients can be treated with more focal therapy followed by WBRT only at relapse. Overall, the current paper reconfirms what has already been well-described in cancer patients with metastatic brain lesions.