INFILTRATIVE ASTROCYTOMAS OF THE THALAMUS

Clinical characteristics and outcome in 57 patients with infiltrative thalamic astrocytomas were analyzed retrospectively. The median patien t age was 22 years (range 1 to 69 years). Fourteen patients had no sur gery, 37 had biopsy, and six had subtotal resection. The histological diagnosis was astrocytoma in 14 patients, anaplastic astrocytoma in 25 , and glioblastoma multiforme in two; two specimens were nondiagnostic . The initial treatment was conventional radiation therapy (RT) in 20 patients (one also received interstitial brachytherapy), RT followed b y chemotherapy in 18, hyperfractionated RT in 17 (one also received ch emotherapy), and chemotherapy alone in two. The median time to tumor p rogression was 47 weeks (range 5 to 388 weeks); median survival was 73 weeks (range 11 to 502 weeks). actuarial 1-, 2-, 3-, and 5-year survi val rates were 67%, 35%, 24%, and 20%, respectively. Tumor progression was usually treated with chemotherapy. The assessed treatment failure was within 2 months after RT in 12 patients in whom the findings of t he neurological and radiological examinations did not correspond. This assessment showed false-negative diagnosis of radiation-induced chang es in five patients (42%); false-positive diagnosis of tumor progressi on could not be ascertained. In univariate Cox proportional-hazards an alysis, histological diagnosis of astrocytoma, age under 18 years, and open biopsy were prognostically favorable features; in multivariate a nalysis, only open biopsy was favorable. Infiltrative astrocytomas of the thalamus carry a dismal prognosis, regardless of the type of treat ment. Hyperfractionated RT does not increase toxicity but its benefit over conventional RT remains unproven.