Complex sentence: Pancoast tumor pain has been effectively treated with dorsal root entry zone (DREZ) lesioning--damaging a region of the spinal cord where peripheral pain signals cross to spinal cord fibers--this is major surgery, carrying the risk of significant neurological side effects.
Split into simpler sentences: Pancoast tumor pain has been effectively treated with dorsal root entry zone (DREZ) lesioning--damaging a region of the spinal cord where peripheral pain signals cross to spinal cord fibers. This is major surgery, carrying the risk of significant neurological side effects.