ANA Discussion Forum
Treatment Options => Radiation / Radiosurgery => Topic started by: KeepSmiling on October 02, 2014, 06:43:36 am
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When I wanted to find medical studies about vestibular schwannomas , here is one of a few possible resources I have used.
Go to http://www.ncbi.nlm.nih.gov/pubmed/
and type in any words that seem relevant. My latest search for “fractionated proton treatment for vestibular schwannomas” yielded the following studies:
1. http://www.ncbi.nlm.nih.gov/pubmed/24725695
Int J Radiat Oncol Biol Phys. 2014 May 1;89(1):113-9. doi: 10.1016/j.ijrobp.2014.01.038.
Pretreatment growth rate predicts radiation response in vestibular schwannomas.
Niu NN1, Niemierko A2, Larvie M3, Curtin H4, Loeffler JS2, McKenna MJ5, Shih HA6.
Author information
Abstract
PURPOSE:
Vestibular schwannomas (VS) are often followed without initial therapeutic intervention because many tumors do not grow and radiation therapy is associated with potential adverse effects. In an effort to determine whether maximizing initial surveillance predicts for later treatment response, the predictive value of preirradiation growth rate of VS on response to radiation therapy was assessed.
METHODS AND MATERIALS:
Sixty-four patients with 65 VS were treated with single-fraction stereotactic radiation surgery or fractionated stereotactic radiation therapy. Pre- and postirradiation linear expansion rates were estimated using volumetric measurements on sequential magnetic resonance images (MRIs). In addition, postirradiation tumor volume change was classified as demonstrating shrinkage (ratio of volume on last follow-up MRI to MRI immediately preceding irradiation <80%), stability (ratio 80%-120%), or expansion (ratio >120%). The median pre- and postirradiation follow-up was 20.0 and 27.5 months, respectively. Seven tumors from neurofibromatosis type 2 (NF2) patients were excluded from statistical analyses.
RESULTS:
In the 58 non-NF2 patients, there was a trend of correlation between pre- and postirradiation volume change rates (slope on linear regression, 0.29; P=.06). Tumors demonstrating postirradiation expansion had a median preirradiation growth rate of 89%/year, and those without postirradiation expansion had a median preirradiation growth rate of 41%/year (P=.02). As the preirradiation growth rate increased, the probability of postirradiation expansion also increased. Overall, 24.1% of tumors were stable, 53.4% experienced shrinkage, and 22.5% experienced expansion. Predictors of no postirradiation tumor expansion included no prior surgery (P=.01) and slower tumor growth rate (P=.02). The control of tumors in NF2 patients was only 43%.
CONCLUSIONS:
Radiation therapy is an effective treatment for VS, but tumors that grow quickly preirradiation may be more likely to increase in size. Clinicians should take into account tumor growth rate when counseling patients about treatment options.
Copyright © 2014 Elsevier Inc. All rights reserved.
PMID:
24725695
[PubMed - indexed for MEDLINE]
http://www.ncbi.nlm.nih.gov/pubmed/11844261
Neurosurgery. 2002 Feb;50(2):270-3; discussion 273-5.
2. Fractionated proton beam radiotherapy for acoustic neuroma.
Bush DA1, McAllister CJ, Loredo LN, Johnson WD, Slater JM, Slater JD.
Author information
Abstract
OBJECTIVE:
This study evaluated proton beam irradiation in patients with acoustic neuroma. The aim was to provide maximal local tumor control while minimizing complications such as cranial nerve injuries.
METHODS:
Thirty-one acoustic neuromas in 30 patients were treated with proton beam therapy from March 1991 to June 1999. The mean tumor volume was 4.3 cm(3). All patients underwent pretreatment neurological evaluation, contrast enhanced magnetic resonance imaging, and audiometric evaluation. Standard fractionated proton radiotherapy was used at daily doses of 1.8 to 2.0 cobalt Gray equivalent: patients with useful hearing before treatment (Gardner-Robertson Grade I or II) received 54.0 cobalt Gray equivalent in 30 fractions; patients without useful hearing received 60.0 cobalt Gray equivalent in 30 to 33 fractions.
RESULTS:
Twenty-nine of 30 patients were assessable for tumor control and cranial nerve injury. Follow-up ranged from 7 to 98 months (mean, 34 mo), during which no patients demonstrated disease progression on magnetic resonance imaging scans. Eleven patients demonstrated radiographic regression. Of the 13 patients with pretreatment Gardner-Robertson Grade I or II hearing, 4 (31%) maintained useful hearing. No transient or permanent treatment-related trigeminal or facial nerve dysfunction was observed.
CONCLUSION:
Fractionated proton beam therapy provided excellent local control of acoustic neuromas when treatment was administered in moderate doses. No injuries to the Vth or VIIth cranial nerves were observed. A reduction in the tumor dose is being evaluated to increase the hearing preservation rate.
PMID:
11844261
[PubMed - indexed for MEDLINE]
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The second study is quite an old one now, 2002. Did nothing newer show in your search?
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The first study isn't about proton therapy
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The first study isn't about proton therapy
That's right and I'd thought it was just a comparison of one technique against the other.
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Range uncertainty is big problem with proton therapy.
Accuracy of proton therapy is typically +- 3mm versus 0.5mm for gamma knife
Proton therapy favours larger tumours as a result.
Will protons gradually replace photons
http://medicalphysicsweb.org/cws/article/research/50584
Another interesting read here
Radiosurgery with photons or protons for benign and malignant tumours of the skull base: a review
http://www.ro-journal.com/content/7/1/210
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Wow! That's a totally different level of accuracy compared with GK or CK. I hadn't realised it couldn't be controlled closely.
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Range uncertainty of protons which is a physics thing.... Will always exist.. The delivery system of protons is less advanced..beam shaping is still a pipe dream.
Small targets for proton therapy are not its strengths.
Which is probably reflected in the poor hearing preservation results.
The cochlear is often a millimetre or two away from the AN.
Radiation doses to the cochlear are now thought to be the biggest link to hearing preservation after radio surgery
Proton therapies strengths are large targets, young patients, organs at risk more than 3mm away.
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Range uncertainty of protons which is a physics thing.... Will always exist.. The delivery system of protons is less advanced..beam shaping is still a pipe dream.
Small targets for proton therapy are not its strengths.
Which is probably reflected in the poor hearing preservation results.
The cochlear is often a millimetre or two away from the AN.
Radiation doses to the cochlear are now thought to be the biggest link to hearing preservation after radio surgery
Proton therapies strengths are large targets, young patients, organs at risk more than 3mm away.
interesting and informative - thanks!
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If you want to research current medical studies go here: http://www.ncbi.nlm.nih.gov/pubmed/
If you have questions about range uncertainty then plug in the words that cause concern and you can see the most current studies.
If so inclined, type the words "range uncertainty proton therapy " or type other words. See the most current studies.
There are several studies from current times- some from 2014 - and some of the studies might be relevant for acoustic neuroma patients. It is worthwhile to keep an open mind.