Late-Delayed Effects of Radiation Therapy
The late-delayed radiation symptoms are most commonly seen in the neurological, neurocognitive, and endocrine systems. Late-delayed radiation effects on the central nervous (CNS) system are iatrogenic injuries that are irreversible and possibly progressive. Neural substrates include vasculopathies and capillary damage, stroke, demyelination, disruption of cellular mitosis, radiation necrosis, diaschisis, destruction of the hypothalamic–pituitary axis, and gliosis. Late-delayed effects often present as leukoencephalopathy within the tumor field; this gross change is more commonly seen on MRI or CT at higher total radiation doses.
Changes have been retrospectively described several months to many years posttreatment (for review, see Armstrong et al. 2004; Crossen et al. 1994; DeAngelis et al. 1989). Declines have been reported using PET and [11C] methionine, an amino acid marker, in gray matter remote from the tumor during several...
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