LONG-TERM GLIOBLASTOMA-MULTIFORME SURVIVORS - A POPULATION-BASED STUDY

Background: Long-term glioblastoma multiforme survivors (LTGBMS) are u ncommon. The frequency which these occur in an unselected population a nd factors which produce these unusually long survivors are unknown. O bjectives: To determine in a population-based study 1) the frequency o f LTGBMS in a population and 2) identify which patient, treatment or t umor characteristics would predict which glioblastoma (GBM) patient wo uld become a LTGBMS, Methods: The Alberta Cancer Registry was used to identify all patients diagnosed with GEM in southern Alberta between 1 /1/75 - 12/31/91, Patient charts were reviewed and histology re-examin ed by a blinded neuropathologist, LTGBMS were defined as (GBM patients surviving greater than or equal to 3 years after diagnosis. Each LTGB MS was compared to three age-, gender-, and year of diagnosis-matched controls to compare patient, treatment, and tumor factors to GEM patie nts without long-term survival. Results: There were 279 GBMs diagnosed in the study period. Five (1.8%) survived greater than or equal to th ree years (range, 3.2-15.8 years). Seven additional long-term survivor s, who carried a diagnosis of GEM, were excluded after neuropathologic review; the most common revised diagnosis was malignant oligodendrogl ioma, LTGBMS (avg,age = 45 years) were significantly younger when comp ared to all GEM patients (avg. age = 59 years, p = 0.0001) diagnosed i n the study period. LTGBMS had a higher KPS at diagnosis (p = 0.001) c ompared to controls, Tumors from LTGBMS tended to have fewer mitoses a nd a lower Ki-67 cellular proliferative index compared to controls. Ra diation-induced dementia was common and disabling in LTGBMS. Conclusio ns: These data highlight the dismal prognosis for GEM patients who hav e both a short median survival and very small chance (1.8%) of long-te rm survival. The LTGBMS were younger, had a higher performance status, and their tumors tended to proliferate less rapidly than control GEM patients. When long-term survival does occur it is often accompanied b y severe treatment-induced dementia.