Phase II trial of conformal radiation therapy for pediatric patients with craniopharyngioma and correlation of surgical factors and radiation dosimetry with change in cognitive function

Object. A Phase II trial of conformal radiation therapy (CRT) for craniopharyngioma was conducted to determine whether the irradiated volume could be safely reduced to decrease effects on cognitive function. Methods. Between July 1997 and January 2003, 28 pediatric patients (median age 7.3 ± 4.12 years) received CRT in whom doses (54-55.8 Gy) were administered to the gross tumor volume (solid and cystic components) surrounded by a 1-cm clinical target volume margin. Patients were evaluated serially with neuropsychometric testing. Statistical analyses were performed to determine the effect of clinical factors and radiation dosimetry on intelligence quotient (IQ). The median follow-up period was 36.6 months (range 24.4-80 months). The estimated 3-year progression-free survival rate was 90.3 ± 7.3%. Three patients experienced local disease progression. Cognitive outcome for patients was adversely affected by the following factors: age younger than 7.4 years (p = 0.001), an interval between symptoms and diagnosis of more than 73 days (p = 0.06), more extensive surgery (p = 0.014), multiple surgical procedures (p = 0.002), diabetes insipidus (p = 0.02), hydrocephalus at diagnosis (p = 0.009), a cerebrospinal fluid shunt (p = 0.005), shunt revisions (p = 0.01), Ommaya reservoir laterality (p = 0.005), and cyst aspirations (p = 0.02). The percentage of total brain, supratentorial brain, or left temporal lobe volumes receiving a dose in excess of 45 Gy had a significant impact on longitudinal IQ. Conclusions. The use of CRT with a 1-cm margin for clinical target volume results in tumor control equivalent to that achieved using conventionally planned radiation therapy. Surgical morbidity and a volume-receiving dose more than 45 Gy are factors affecting longitudinal IQ after CRT in patients treated for craniopharyngioma.