ASTRO Guideline for glioblastoma

[subatomicdoc]

I just got my Practical Radiation Oncology. I am surprised at ASTRO's gloss-over on target volume margins, which only got a single self-citation not nearly as relevant to the topic as several other papers.

NCCN still pushes this very large 2-3 cm margin despite the fact a lot of academic centers don't use them.

I'll let others correct me but I believe the rationale for RTOG margins is a Laurie Gaspar paper from 1992:
http://www.ncbi.nlm.nih.gov/pubmed/1512163

What do you think?

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[medgator]

Those margins do get ridiculous and I think IRL, most people trim it down quite a bit. There is no way those 2-3 margins will fly for example with a temporal lobe tumor up against the ON/OC and brainstem in order respect critical structures.

 

[Palex80]

We nowadays treat with a 1.5cm CTV-margin around cavity + contrast enhanced structures, clip on midline/bone/ventricles/tentorium etc. then add another 5mm for PTV.
Probably 5mm for PTV is still too big, 3mm would be good too.

In my humble opinion 90% of recurrences involve the GTV area. There are distance recurrences too, but rarely isolated ones.

 

[seper]

Well, in those cases you'd reduce CTV margins "at the natural barriers". RTOG protocols are clear about that. I've seen enough "marginal misses" with GBM, and continue to use 2 cm margins.

 

[subatomicdoc]

Well, in those cases you'd reduce CTV margins "at the natural barriers". RTOG protocols are clear about that. I've seen enough "marginal misses" with GBM, and continue to use 2 cm margins.

I agree based upon what you read in NRG and EORTC. But the data say otherwise:

Emory http://www.ncbi.nlm.nih.gov/pubmed/20399036 n=62
Michigan http://www.ncbi.nlm.nih.gov/pubmed/11896114 n=34
Wake Forest http://www.ncbi.nlm.nih.gov/pubmed/23211224 n=161
Rome, Italy http://www.ncbi.nlm.nih.gov/pubmed/20855119 n=105
U Alabama Birmingham http://www.ncbi.nlm.nih.gov/pubmed/24906388 n=95
Birmingham (UK) http://www.ncbi.nlm.nih.gov/pubmed/23385995 n=105

A review of the topic in PRO does much better justice than ASTRO's guidelines. Also points out more morbidity with larger fields.
http://www.ncbi.nlm.nih.gov/pubmed/26952812

So NCCN, NRG now use large margins, meaning more potential unneccesary morbidity. ASTRO should have either avoided the topic or done a proper analysis.

 

[Reaganite]

I personally do something in between. If I have an RO resection, methylated promotor, I give patient benefit of the doubt and follow the RTOG guidelines. You send me a patient with gross residual disease and/or disease that's rapidly recurred from the interval from surgery to XRT, I don't see the point in big fields. In my experience, all these patients progress in field either during RT or shortly after.

I agree based upon what you read in NRG and EORTC. But the data say otherwise:

Emory http://www.ncbi.nlm.nih.gov/pubmed/20399036 n=62
Michigan http://www.ncbi.nlm.nih.gov/pubmed/11896114 n=34
Wake Forest http://www.ncbi.nlm.nih.gov/pubmed/23211224 n=161
Rome, Italy http://www.ncbi.nlm.nih.gov/pubmed/20855119 n=105
U Alabama Birmingham http://www.ncbi.nlm.nih.gov/pubmed/24906388 n=95
Birmingham (UK) http://www.ncbi.nlm.nih.gov/pubmed/23385995 n=105

A review of the topic in PRO does much better justice than ASTRO's guidelines. Also points out more morbidity with larger fields.
http://www.ncbi.nlm.nih.gov/pubmed/26952812

So NCCN, NRG now use large margins, meaning more potential unneccesary morbidity. ASTRO should have either avoided the topic or done a proper analysis.

 

[scarbrtj]

"Old margins" need updating to "new" margins. If it said 2 cm margins 20 years ago, please oh please do not do more than 1.5 cm today--because they're equivalent.
http://www.redjournal.org/article/S0360-3016(05)01014-X/pdf