How would you treat this: Case 1

[Palex80]

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Hello everybody.
Almost every week I see a patient, treated by me or a colleague, where different opinions exist concerning his/her proper treatment.
I'd like to ask you, how you would treat such a patient, to get a feeling of what other colleagues would do

Case 1
60 year old lady with primary metastatic breast cancer. Diagnosed 4 months ago with multiple cerebral filiae (at least 5). First line treatment was WBRT with 10x3 Gy and antihormonal treatment. The patient has been sent to us again now, 3 months after the WBRT with 3 brain metastases (the rest are gone). Patient has only few neurological symptoms currently.
Extrathoracic tumor load only in breast+axilla, no visceral metastases.
Current lesions:
1. Is about 2 cms, in the pons/brain stem
2. Is about 2 cms, parietal
3. Is about 0,5 cms, occipital

We want to give the patient stereotactic radiation for the 3 brain metastases and were thinking of possible fractionation alternatives.
The pons/brain stem metastasis is obviously the dose limiting one.
Following fractionations have been suggested:
1. SRS with 1x16 Gy (80% isodose)
2. SFS with 6x5 Gy (80% isodose)
3. SFS with 3x7 Gy (80% isodose)

How would you treat?

 

[Gfunk6]

Tough situation. After talking it over with one of our graduating seniors, I think we would prefer SRS of 5 Gy x 5 over 16 Gy x 1. The key, obviously, is to be really conforomal though it is not entirely clear if the pt would live long enough to experience complications.

For the mets outside the BS we (assuming met size <= 2 cm) we try to treat to a single fraction dose of at least 18 Gy using SRS.

 

[G'ville Nole]

Do you use a headframe for your SRS? If so, while she's got the frame on, why not do single fraction SRS on the parietal/occipital mets, and deliver the first of a hypofractionated treatment (i.e. 5-7 Gy) to the BS using SRS as well. Granted, the subsequent treatments will differ dosimetrically, but you won't get better precision or conformality than SRS, and while you've got the frame on, why not?

 

[Palex80]

We use a headframe for SRS but we actually do SRS at the moment only for patients with benign diseases.
With the advances in mask immobilization systems, CBCT and very tight collimation with micro-MLCs I do not see any advantages of SRS over SFS in malignant diseases, other than having to treat the patient only once.

 

[medgator]

We use a headframe for SRS but we actually do SRS at the moment only for patients with benign diseases.
With the advances in mask immobilization systems, CBCT and very tight collimation with micro-MLCs I do not see any advantages of SRS over SFS in malignant diseases, other than having to treat the patient only once.

Costs, pt convenience etc. need to be taken into account as well. When it comes to things like treating a benign disease like TN, I wouldn't feel safe doing anything else except single-fraction SRS with a headframe using gamma-knife.

 

[Palex80]

Costs, pt convenience etc. need to be taken into account as well. When it comes to things like treating a benign disease like TN, I wouldn't feel safe doing anything else except single-fraction SRS with a headframe using gamma-knife.

I agree, but LINAC-based SRS is also an option here.

As far as patient convenience is concerned:
Surely a signle fraction SRS is more convenient than 3-5 fractions SFS, but with SRS:
a) you get the stereotactic ring attached to the scull, which is not that ... convenient.
b) you have to wait between stereotactic ring fixation for the planning to finish before getting irradiated.

IMHO SFS is more convenient than SRS and probably has less side effects as well (at least from what we know in acousticus neurinoma).
However, when treating a benign disease where no margin is necessary and which is surrounded by a lot of healthy tissue (like for example in TN as you said or in the case of AVM), I would opt for SRS (linac or gammaknife based).

 

[G'ville Nole]

I have no quarrel with SFS using IGRT/micro-MLC's as you allude to, it's just that I don't have those available to me. One of my colleagues trained on the same linac-based unit as I did, and now swears by BrainLab.

We use no margin for brain mets. If you look at the dose received by the 2 or 3mm expansion of your GTV in a radiosurgery plan, it seems clear to me that you don't need to. I AM leery of SRS when you get close to the brainstem, though, including larger vestibular schwannomas that press on the CP angle. I agree with you on fractionating in those situations.

 

[Gfunk6]

Here's an article published by UCSF describing our experience using SRS for brainstem mets w/ and w/o prior WBRT. 16 Gy seemed like a safe and effective dose except for mets from melanoma/RCC or mets greater than 1 cm.

 

[Palex80]

Thanx for the article. Most mets irradiated in the paper were rather smaller ones and one has the feeling, that the UCSF crew tried to limit dose in larger mets (resulting in higher failure rates).

I'll let you all know what we decided to do and how it worked out.

 

[Brim]

Diagnosed 4 months ago with multiple cerebral filiae

It's interesting to hear brain mets called filiae, but I guess that's what they are.

 

[Palex80]

It's interesting to hear brain mets called filiae, but I guess that's what they are.

Sorry, that's just latin terminology. Mets is fine too.

 

[Palex80]

Ok we started treatment today:

It's 6x5 Gy for both mets (90% isodose) with a minimal margin.