Perhaps one of the reasons proton beam therapy is rarely mentioned for treating acoustic neuromas is the price, which is usually much more expensive than photon machines like Cyberknife, Gamma Knife, etc. and hospitals don't feel justified making that investment. It may also be due to difficulty in getting Medicare to approve its use. On the other hand, incremental improvements in photon machines continue to refine their beneficial properties. Moreover, in a paper titled: Protons vs Photons for Brain and Skull Base Tumors released in 2018, Ahmed et al state, when referring to a possible highly anticipated benefit of decreased risk of long-term radiotherapy-related adverse effects secondary to reduced doses to normal tissues, that "This highly anticipated benefit, however, awaits long-term clinical and cost-effectiveness data." This technical paper is worth a read for those considering the pros and cons of proton v photon therapy. Coincidentally, I talked with MGH today about radiation treatment, and the head of the proton center said he wouldn't use proton therapy, but rather their Varian TrueBeam radiosurgery machine, with frameless mask and real time computer tracking. I was surprised to hear this when in previous conversations, that doctor said he would use the proton machine. Apparently, he believes it is more effective for AN treatments. Or, could it be insurance issues?