Clinical Trial: RCT of the 4mm vs. the 8mm Collimator for GKR of Brain Micrometastases

Study Status: Recruiting
Recruit Status: Recruiting
Study Type: Interventional

Official Title: Optimal Radiation Method for Gamma Knife Radiosurgery of Brain Micrometastases: A Multi-centre Randomised Clinical Trial (RCT) of the 4mm vs. the 8mm Collimator.

Brief Summary:

Gamma Knife Radiosurgery (GKR) is a well-established treatment modality for brain metastasis (Chiou 2013; Salvetti, Nagaraja et al. 2013). Large multicentre series have been published on patients with single and multiple cerebral metastases, treated with GKR over a period of 30 years (Karlsson, Hanssens et al. 2009). Multiple institutions have reported a consistently high local tumour control rate of 80%-90% following GKR (Chang, Lee et al. 2000; Da Silva, Nagayama et al. 2009; Salvetti, Nagaraja et al. 2013).

There is controversy over the use of GKR and/or Whole Brain Radiotherapy (WBRT) in patients with multiple metastases. WBRT provides a lower rate of distant recurrences, whereas GKR achieves good local control of treated lesions without the deleterious side effects of radiotherapy (Lippitz, Lindquist et al. 2014). This discussion is mainly focused on the risk of distant recurrences, which is lower if WBRT is given. There is evidence showing that Radiosurgery (RS) based on high contrast/resolution stereotactic MRI decreases the incidence and lengthens the time to distant recurrences (Hanssens, Karlsson et al. 2011). As a result, the current tendency is to treat all the lesions visible in high contrast/resolution images the day of Gamma Knife; which is followed by regular MRI follow ups and subsequent GKR for distant recurrences in order to avoid/delay WBRT.

It has been estimated that more than a half of distant recurrences will grow from tumour cells that were already in the brain (as micrometastases) when radiosurgery is delivered, but not much has been studied on the optimal prescription and radiation delivery method for these lesions. There is controversy over which collimator should be used when treating micro-metastases (BmM). These lesions can either be treated with the 4mm collimator at an isodose between the 40

Detailed Summary:
Sponsor: University College, London

Current Primary Outcome: Local control rate (LCR) [ Time Frame: up to 24 months after treatment ]

LCR will be evaluated through volumetric assessment of the lesion the day of Gamma Knife and in subsequent follow up MRI scans


Original Primary Outcome: Same as current

Current Secondary Outcome: Adverse radiation effects (ARE) [ Time Frame: up to two years ]

The following radiological and clinical outcomes will be used to assess ARE:

Bleeding from randomised lesions, Perilesional radiation induced necrosis, Severe peri-lesional oedema, New onset or worsened neurological deficit attributable to a randomised lesion



Original Secondary Outcome: Same as current

Information By: University College, London

Dates:
Date Received: August 18, 2014
Date Started: September 2014
Date Completion: April 2021
Last Updated: March 19, 2015
Last Verified: March 2015