Current state of proton therapy for tumors of the central nervous system in Spain: physical bases, indications, controversies and perspectives.

The unique biophysical properties of proton therapy (PT), regarding the precise dose distribution, a remarkable better sparing of surrounding normal tissues, and the decreasing costs have promoted the spread of this technique worldwide. In Spain, eleven new PT centers, added to the currently two in function, are expected to be available in the near future. Indications for PT are currently evolving.