Ingrid, sorry to read of your diagnosis. I too have Meningeal Mets, and three Brain mets. You probably know quite a bit about this already but as others may not I will try and explain things, so that we all know what we're talking about, and don't start making suggestions that are unsuitable.
Meningeal metastases are really quite different to Brain Metastases. Brain metastases are those in the Brain, whereas Meningeal Metastases are mets that exist in the membrane surrounding the Brain (the Meninges). In order to understand how this impacts on treatment options it's first necessary to understand how the membrane is constructed, as treatment options hang on what part of the membrane is effected, how much involvement of the membrane there is, and how likely it is that cancer cells have entered the spinal fluid.
The membrane consists of three layers. The layer closest to the brain is the Pia Mater, the middle layer is called the Arachnoid Mater and the outer layer closest to the skull is the Dura
If Mets are localised within the Dura and there is no involvement of the spinal fluid then all the treatments used for Metastases in the Brain would be appropriate (Lap/Cap, Tamoxifen, Stereotactic RT and WBRT). The reason SRT would be possible is because the Dura is a hard outer layer, and mets can be targeted , providing there are not too many. However, if you wanted Stereotactic RT treatment for Dural Mets you would have to self fund because NHS England only fund Mets localised within the Brain which are under a total volume. The other problem is that many doctor assume that if Mets are observed within the Dura there is a chance they could have penetrated futher into the Dura, and treatment would then not be worthwhile.
If Mets are in the Pia Mater or Arachnoid Mater, Chemo's and other systemic treatments that cross the Blood Brain barrier, would also be an option, but SRT would not as these two layers are jelly like structures, and so mets tend to thread throughout them, and there is no target as such. However WBRT is still an option as this does not require a target in the same way as SRT.
If Mets have spread throughout the three layers of the meninges, there is a possibility that it could have passed into the spinal fluid, and that makes treatment more difficult (but if doctors suspect this they usually do a Spinal Tap to search for cancer cells). If this test confirms involvement in the spinal fluid things can be more tricky. Systemic treatments are still available, but the delivery of it them is more difficult. It's not just that systemic treatments have to penetrate the Blood Brain Barrier, they also have to get into the spinal fluid as well - and the only way to do this is with intrathecal infusions into the spine. Similarly RT is much more difficult because it is not possible to irradiate the entire spine, and usually there is no target (unless there is a collection of cells at a particular junction).
In any case, even if all the layers of the meninges had been crossed and the spinal fluid breached, all is not lost. Intrathecal infusions can keep things at bay (and I have read of people surviving a few years with this treatment). Similarly, RT can be used if cells collect in a particular area , or are having an effect on the rest of the central nervous system, and this too can hold things at bay.
To end this lengthy post I would like to say the important thing to remember is just because Mets have been observed in one place, doesn't mean it's a forgone conclusion that they will go to X,Y or Z. Sometimes these things make an appearance and then just do nothing. In my case, I was diagnosed with three Mets in the Brain, and more localised within the Dura just before last Christmas (2012). Unfortunately, SRT is not an option for me because my Dural Mets are a bit too extensive and in any case would make me ineligible NHSfunding . However, I have been taking Lapatanib and Capecitabine since diagnosis, and no other BM's have popped up and the existing ones have halved in size. Eventually if the Lap Cap fails and my BM's become symptomatic I will have WBRT, and pray it is as successful for me as it has been for others.
Anyway I hope this post is helpful. I am not a medical professional. I am simply passing on what has been explained to me at the Marsden. Best of luck with your treatment..
