Gamma Knife surgery for treatment of 5-15 brain mets

[Lani]

J Neurosurg. 2013 Mar 29. [Epub ahead of print]
Gamma Knife surgery for the treatment of 5 to 15 metastases to the brain.
Salvetti DJ, Nagaraja TG, McNeill IT, Xu Z, Sheehan J.
Source
Department of Neurological Surgery, University of Virginia, Charlottesville, Virginia.
Abstract
Object It has been generally accepted that Gamma Knife surgery (GKS) is an effective primary or adjunct treatment for patients with 1-4 metastases to the brain. The number of studies detailing the use of GKS for 5 or more brain metastases, however, remains minimal. The aim of the current retrospective study was to elucidate the utility of GKS in patients with 5-15 brain metastases. Methods Patients were chosen for GKS based on prior MRI of these metastatic lesions and a known primary cancer diagnosis. Magnetic resonance imaging was used post-GKS to assess tumor control; patients were also followed up clinically. Overall survival (OS) from the date of GKS was used as the primary end point. Statistical analysis was performed to identify prognostic factors related to OS. Results Between 2003 and 2012, 96 patients were treated for a total of 704 metastatic brain lesions. The histology of these lesions varied among non-small cell lung cancer (NSCLC), breast cancer, melanoma, renal cancer, and other more rare carcinomas. At the initial treatment, 18 of the patients (18.8%) were categorized in Recursive Partitioning Analysis (RPA) Class 1 and 77 (80.2%) in RPA Class 2; none were in RPA Class 3. The median number of treated lesions was 7 (mean 7.13), and the median planned treatment volume was 6.12 cm3 (range 0.42-57.83 cm3) per patient. The median clinical follow-up was 4.1 months (range 0.1-40.70 months). Actuarial tumor control was calculated to be 92.4% at 6 months, 84.8% at 12 months, and 74.9% at 24 months post-GKS. The median OS was found to be 4.73 months (range 0.4-41.8 months). Multivariate analysis demonstrated that RPA class was a significant predictor of death (HR = 2.263, p = 0.038). Number of lesions, tumor histology, Graded Prognostic Assessment score, prior whole-brain radiation therapy, prior resection, prior chemotherapy, patient age, patient sex, controlled primary tumor, extracranial metastases, and planned treatment volume were not significant predictors of OS. Conclusions In patients with 5-15 brain metastases at presentation, the number of lesions did not predict survival after GKS; however, the RPA class was predictive of OS in this group of patients. Gamma Knife surgery for such patients offers an excellent rate of local tumor control.
PMID: 23540265 [PubMed - as supplied by publisher]

[Joan M]

Lani,

Thanks for posting this.

I need a layman's interpretation! I was not familiar with the RPA statistical method and looked it up, but I'm unclear about the class distinction. Does that refer to how far down the decision tree? How does RPA class apply here.

Thanks much for the clarification!
Joan

[Boo]

Interesting article and good news for me right now but what is Recursive partitioning analysis or RPA. Can anyone describe what this is. Thank you. Anne

[Jackie07]

[http://en.wikipedia.org/wiki/Performance_status]

Not sure if this is the right answer:

Int J Radiat Oncol Biol Phys. 1997 Mar 1;37(4):745-51.
Recursive partitioning analysis (RPA) of prognostic factors in three Radiation Therapy Oncology Group (RTOG) brain metastases trials.

Gaspar L, Scott C, Rotman M, Asbell S, Phillips T, Wasserman T, McKenna WG, Byhardt R.
Source

Wayne State University, Detroit, MI 48201, USA. gasparl@kci.wayne.edu

Abstract

PURPOSE:

Promising results from new approaches such as radiosurgery or stereotactic surgery of brain metastases have recently been reported. Are these results due to the therapy alone or can the results be attributed in part to patient selection? An analysis of tumor/patient characteristics and treatment variables in previous Radiation Therapy Oncology Group (RTOG) brain metastases studies was considered necessary to fully evaluate the benefit of these new interventions.
METHODS AND MATERIALS:

The database included 1200 patients from three consecutive RTOG trials conducted between 1979 and 1993, which tested several different dose fractionation schemes and radiation sensitizers. Using recursive partitioning analysis (RPA), a statistical methodology which creates a regression tree according to prognostic significance, eighteen pretreatment characteristics and three treatment-related variables were analyzed.
RESULTS:

According to the RPA tree the best survival (median: 7.1 months) was observed in patients < 65 years of age with a Karnofsky Performance Status (KPS) of at least 70, and a controlled primary tumor with the brain the only site of metastases. The worst survival (median: 2.3 months) was seen in patients with a KPS less than 70. All other patients had relatively minor differences in observed survival, with a median of 4.2 months.
CONCLUSIONS:

Based on this analysis, we suggest the following three classes: Class 1: patients with KPS > or = 70, < 65 years of age with controlled primary and no extracranial metastases; Class 3: KPS < 70; Class 2- all others. Using these classes or stages, new treatment techniques can be tested on homogeneous patient groups.

[Joan M]

Jackie,

That pretty much explains it in a nutshell! And this is very good news for women who have had a brain met as their only site of metastasis.

Thanks much!

Joan