Skull base tumors: Viewpoint—fractionated radiotherapy or stereotactic radiotherapy

Abstract

Amongst skull base tumors, chordomas (CHOR), chondrosarcomas (CS), and paragangliomas (PGLs) represent major therapeutic challenges. For CHOR and CS, even maximally safe surgery is followed by a high rate of local recurrence or progression. Thus high-dose, high-precision radiotherapy needs to be given postoperatively, and this is well accomplished by particle therapy. With proton beam radiotherapy (PBT), local control rates are good for CHOR and excellent for CS, with a limited risk of complications. Therefore PBT is often considered to be the standard treatment for these tumors. However postoperative RS and STRT are also able to deliver safely high-dose radiotherapy to CHOR and CS. Results demonstrate that they can yield good to excellent local control rates, and in the absence of PBT they can reasonably be used as alternative therapeutic approaches. In large tumors, where RS may be followed by an increased risk of complications, STRT, which combines the precision of RS and the biological advantage of fractionation, should be preferred. Like for CHOR and CS, a genuine complete resection is rarely possible for PGL, or at the sacrifice of cranial nerves. Conformal, fractionated external beam radiotherapy with moderate-to-high doses is followed by an excellent long-term local control. As PGLs are slow-growing tumors, they shrink also slowly and thus local control after radiotherapy should be defined as the absence of clinical or radiological progression. Results after RS and STRT are also excellent, but like for CHOR and CS, STRT is preferred in case of large tumors.​