help needed-WBRT

[zobell]

Hey all,
Im doing an assignment for the treatment I would give the following patient;
58 year old woman, presents with nausea, headaches and short term memory loss. CT and MRI show multiple (5) intracranial lesions with vasogenic oedema and ring enhancement. She has no known primary so a CT TAP was done and a 5.1cm lesion in the rUL was noted with right mediastinal, hilar and supraclavicular lymphadenopathy. Biospy indicated NSCLC stage IV - squamous type. KPS of 80 so she would be RPA II, as the primary is not controlled?

How would other people treat this patient? I have said because of the multiple lesions no surgery and because of high overall tumour volume no SRS. 16mg a day of Dexamethasone. She has no symptoms of her primary disease so I am unsure with regards to chemotherapy; should I give her chemo after her WBRT, or at all? if so, what agent should I use. As she is SCC it can be presumed that she is EGFR and ALK neg and so I have not mentioned Erlotinob...
Am not using a radiosensitizer as I live in Ireland and its use is uncommon here.

Also with regards to her plan, I am used to the gantry being angled posteriorly by 2 or 3 degrees to avoid divergence to the contralateral eye, but her gantry angles are larger, 277 degrees and 83 degrees. Would it be for the same reason?
sorry if this was a silly question, still a student!!

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[OTN]

What's the size of the largest intracranial met? I wouldn't yet rule out SRS based on what I've heard so far. She's on 16 mg dex a day, so I assume there's a decent amount of edema, etc. If there's one main intracranial lesion causing swelling/symptoms, you could always resect that met if technically possible, then treat with SRS to the tumor bed and the remaining lesions.

My bias over the last 7+ years has moved increasingly towards SRS instead of WBRT, and the data in my opinion continues to help point in that direction as well.

 

[zobell]

What's the size of the largest intracranial met? I wouldn't yet rule out SRS based on what I've heard so far. She's on 16 mg dex a day, so I assume there's a decent amount of edema, etc. If there's one main intracranial lesion causing swelling/symptoms, you could always resect that met if technically possible, then treat with SRS to the tumor bed and the remaining lesions.

My bias over the last 7+ years has moved increasingly towards SRS instead of WBRT, and the data in my opinion continues to help point in that direction as well.

thanks for your reply! all her mets were less than 3cm! She has already had the treatment-dex and WBRT- I just have to review it and give rationale for the decisions made, and I am thinking the same thing about the SRS, I cannot see a reason for not giving it. Also there was no info on chemo in her notes which is why I wondered about that.

 

[seper]

would not do SRS to 5 lesions in a lung cancer patient

 

[zobell]

would not do SRS to 5 lesions in a lung cancer patient

Thanks for your reply! Is there any literature or reasons you would not? kind regards

 

[Gfunk6]

I concur complete with OTN.

 

[Palex80]

I'd still do WBRT.
Surely there is mounting evidence, that you can offer SRS for these patients, however 5 lesions and an SCC histology is just too much in my opinion. If it was an adeno Ca, I would think twice, since the patient have carried some mutation doubling her OS.
Looking however at the overall state of the patient, she probably has a bad prognosis.
She would even qualify for the UK trial testing WBRT vs. steroids, right?

Concerning the gantry angles, you are right. One can do that to limit dose to the contralateral eye. Some do half beam too. I presume her angles are different because of how she is lying under the mask in the CT? Or was is a simulator based planning?

I'd give her the WBRT and have the med onc look at her a couple of weeks later to decide, if she can have chemo or not. If the CNS-symptoms do not better and she needs these awful lots of steroids, then her prognosis is really bad and chemo won't offer her any benefit. That would be my approach. You may consider any other palliative measures, like stenting or palliative RTx to the mediastinum/hilus if there is lots of compression/occlusion due to the primary or lymph nodes.
As far as chemo is concerned, I'd give platinum with gemcitabine. If she's not doing well stick to Carbo, don't try Cis.

 

[Brim]

The gantry angles for making the beams non-divergent at the eyes depends on the field geometry -- namely the distance between the isocenter and the eyes (as seen on Beam's Eye View). If you place your isocenter right at the eyes, your gantry angles will be 270 and 90. But most of the time the isocenter is in the middle of the head and you'll get a tilt of a few degrees from opposing beams in order to create non-divergence. The farther back the isocenter, the larger the tilt. For us, it's usually 5 degrees ... We must have bigger heads in the USA.

 

[zobell]

The gantry angles for making the beams non-divergent at the eyes depends on the field geometry -- namely the distance between the isocenter and the eyes (as seen on Beam's Eye View). If you place your isocenter right at the eyes, your gantry angles will be 270 and 90. But most of the time the isocenter is in the middle of the head and you'll get a tilt of a few degrees from opposing beams in order to create non-divergence. The farther back the isocenter, the larger the tilt. For us, it's usually 5 degrees ... We must have bigger heads in the USA.

Thanks for your reply. I read that in patients with frontal and cerebellar mets some ROs can be reluctant to use this angling due to fear of underdosing lesions located in the frontal lobe and in the cerebellum, but this to me did not make sense, once the field borders are applied with appropriate coverage surely this would not occur?

 

[zobell]

I'd still do WBRT.
Surely there is mounting evidence, that you can offer SRS for these patients, however 5 lesions and an SCC histology is just too much in my opinion. If it was an adeno Ca, I would think twice, since the patient have carried some mutation doubling her OS.
Looking however at the overall state of the patient, she probably has a bad prognosis.
She would even qualify for the UK trial testing WBRT vs. steroids, right?

Concerning the gantry angles, you are right. One can do that to limit dose to the contralateral eye. Some do half beam too. I presume her angles are different because of how she is lying under the mask in the CT? Or was is a simulator based planning?

I'd give her the WBRT and have the med onc look at her a couple of weeks later to decide, if she can have chemo or not. If the CNS-symptoms do not better and she needs these awful lots of steroids, then her prognosis is really bad and chemo won't offer her any benefit. That would be my approach. You may consider any other palliative measures, like stenting or palliative RTx to the mediastinum/hilus if there is lots of compression/occlusion due to the primary or lymph nodes.
As far as chemo is concerned, I'd give platinum with gemcitabine. If she's not doing well stick to Carbo, don't try Cis.

Thanks for your reply! Also would my patient definitely be considered to have uncontrolled primary disease although she does not have any symptoms of her primary (lung), seeing as she has never been treated for this.

 

[Gfunk6]

Do you not do CT sims for whole brain? If you do, can customize beam angles as needed.

 

[Palex80]

Sorry, I mistead the angles. 7 degrees seem fine, it has to do with the isocenter position.
I initially thought the patient's head was rotated.

 

[zobell]

Sorry, I mistead the angles. 7 degrees seem fine, it has to do with the isocenter position.
I initially thought the patient's head was rotated.

Thanks for your reply. I read that in patients with frontal and cerebellar mets some ROs can be reluctant to use this angling due to fear of underdosing lesions located in the frontal lobe and in the cerebellum, but this to me did not make sense, once the field borders are applied with appropriate coverage surely this would not occur?

 

[Palex80]

That depends on whether you are using CT based planning or not

 

[zobell]

That depends on whether you are using CT based planning or not

Its CT based for my patient, so would it be underdosing the cerebellum or frontal lobe using these gantry angles of 7 degrees off? Also do you think this would be an isocentric technique or one that is prescribed to midplane?

 

[zobell]

6MV energy

 

[ramsesthenice]

I have resisted saying something for as long as I can. I think people have made great points and I am not trying to downplay anything anyone has said.

At our institution we spend more time in our sim review every day talking about whole brain cases and who should or shouldn't get SRS. Lots of time arguing about angling the gantry to avoid lenses, move this MLC a mm to give enough margin on the cribiform, etc. But as our most senior attending frequently points out, its 99% academic for this population. Obviously some populations do better but by in large patients with brain mets don't live all that long and their QOL is about to nose dive because of their disease. Not down playing the toxicities of what we do, they are real.

I actually have a real problem with the amount of publicity that SRS vs WBRT toxicity gets because a lot of non-radiation oncologists are mis-interpreting the data. WBRT has a place and really benefits patients that need it. Several of our med onc's simply won't send patients for WBRT anymore. More than 4 brain mets = clinical trial in their minds. Thanks to a presentation at ASCO this year our PRB (all med oncs) would not renew our participation in N107c (post op SRS vs WBRT) because they felt is was unethical to continue treating with whole brain.

 

[seper]

unethical to continue treating with whole brain? jesus.

 

[Gfunk6]

It's true that many MDs in our community have a very poor understanding of what whole brain radiation is or what it is trying to achieve. If you poll them, probably the majority will say that it takes five weeks to deliver and gives you neuro-toxicity to the same level as advanced stage dementia. Ridiculous.

 

[medgator]

unethical to continue treating with whole brain? jesus.

Yup. Ridiculous. Whole brain is cheap and effective and imo still has a place in the treatment of brain mets......unless someone has 5+ brain Mets and is young with a kps of 100 and minimal extracranial disease, they should be getting wbrt first imo, especially when it comes to lung cancer

 

[OTN]

I have resisted saying something for as long as I can. I think people have made great points and I am not trying to downplay anything anyone has said.

At our institution we spend more time in our sim review every day talking about whole brain cases and who should or shouldn't get SRS. Lots of time arguing about angling the gantry to avoid lenses, move this MLC a mm to give enough margin on the cribiform, etc. But as our most senior attending frequently points out, its 99% academic for this population. Obviously some populations do better but by in large patients with brain mets don't live all that long and their QOL is about to nose dive because of their disease. Not down playing the toxicities of what we do, they are real.

I actually have a real problem with the amount of publicity that SRS vs WBRT toxicity gets because a lot of non-radiation oncologists are mis-interpreting the data. WBRT has a place and really benefits patients that need it. Several of our med onc's simply won't send patients for WBRT anymore. More than 4 brain mets = clinical trial in their minds. Thanks to a presentation at ASCO this year our PRB (all med oncs) would not renew our participation in N107c (post op SRS vs WBRT) because they felt is was unethical to continue treating with whole brain.

I've been able to allay some of my colleague's fears by treating all high-functioning patients with hippocampal-sparing IMRT when WBRT is indicated. While my experience is obviously anecdotal, my patients treated with this method have done VERY well. Might be something to consider introducing.

I disagree with your senior attending. I have a good collection of patients who are doing well 2 or even 3 years out with brain mets after being treated with WBRT. Sure, I also have a group of patients who didn't do well, but it's by no means a homogeneously hopeless population.

 

[ramsesthenice]

I've been able to allay some of my colleague's fears by treating all high-functioning patients with hippocampal-sparing IMRT when WBRT is indicated. While my experience is obviously anecdotal, my patients treated with this method have done VERY well. Might be something to consider introducing.

I hear what you are saying. Im not sure it would help me here. Some of these folks are just irrational and most of these decisions are self-serving as much as anything (though I usually can't say that publicly).

I personally don't plan to do HS WBRT without really high quality data mainly because in my experience the acute toxicity of WBRT (fatigue mostly) is harder on patients than the long-term effects. HS WBRT can't be any better as far as acute toxicity goes. Like you, our clinic has a lot of people several years out from WBRT and most of them really do quite well with minimal complaints about long-term function. Im not really convinced people will really function much better with in the long run with HS WBRT compared to WBRT. Im sure if you look hard enough you can measure something, but as far as day to day function, I have a hard time seeing it. As always, Im open to being wrong.

 

[Areion]

interesting string. I think there are a lot of benefits to WBRT if careful consideration is made to overall systemic disease status, number of intracranial mets; histology; KPS, and need for chemotherapy. Once deciding on WBRT, a question that sometimes comes up is whether people consider using the standard "box" shape WBRT field, as opposed to shaping the 3D conformal field such that the dose to the scalp is limited (as long as the dosimetry shows good dose to brain). there were a couple of nonsignificant IMRT studies (I wouldn't do IMRT in this case) but does anyone have good experience treating modified WBRT fields to give lesser dose to the scalp?