[Usefulness of 3D conformal radiation therapy for reduction of radiation-induced white matter injury].
The usefulness of three-dimensional conformal radiation therapy(3DCRT) in decreasing radiation-induced white matter changes(WMC) was assessed. Thirty-seven patients(age 5-77 years, mean 42 years; male/female = 11/26) with primary intracranial tumors received 40 Gy or more, and were followed up with MRI for more than one year. Thirty-four patients underwent chemotherapy(with a platinum drug, 16; without a platinum drug, 18). Nineteen were treated with 3DCRT (radiation dose, range 60-64 Gy, mean 60.2 Gy; maximum width of radiation field, range 7-16 cm, mean 12.5 cm) and 18 were treated with non-3DCRT (radiation dose, range 40-62.4 Gy, mean 53.4 Gy; maximum width of radiation field, range 4-19 cm, mean 12.3 cm). WMC occurred in 37% of the 3DCRT group and 50% of the non-3DCRT group. Among the patients with WMC, Karnofsky performance scale(KPS) deteriorated in none of the 3DCRT group, whereas KPS deteriorated in 3 of 9 in the non-3DCRT group. All the patients with deterioration of KPS were at least 50 years of age. KPS did not strictly correlate with the severity of white matter changes on MRI. Chemotherapy with a platinum drug increased the incidence of WMC. Age(< 50 years vs. > or = 50 years), gender, radiation technique(3DCRT vs. non-3DCRT), radiation dose(< 60 Gy vs. > or = 60 Gy), maximum field-size(< 12 cm vs. > or = 12 cm), and maximum boost-field size(< 10 cm vs. > or = 10 cm) were not relevant to the incidence and severity of WMC. Though 3DCRT did not decrease the incidence and severity of white matter change on MRI, it may be useful to preserve the KPS, especially for older patients.