Purpose: To describe (1) the use of surgery and radiotherapy (RT) in the treatment of patients with glioblastoma (GBM) in Ontario, (2) survival, and (3) proportion of survival time spent in the hospital after diagnosis.
Methods and materials: We performed a population-based cohort study of all Ontario Cancer Registry (OCR) cases of GBM diagnosed between 1982 and 1994. We linked OCR records, hospital files containing surgical procedure codes from the Canadian Institute for Health Information, and province-wide RT records. We studied the odds of treatment using multivariate logistic regression. We expressed the time spent in the hospital as the mean number of days per case, and as a proportion of the interval between diagnosis and death, or 24 months following diagnosis, whichever came first. We used the life-table method and Cox proportional hazards regression to describe survival.
Results: The proportion of patients with GBM undergoing any surgery directed at the tumor varied with age (p < 0.0001) and region of residence (p < 0.0001). The proportion undergoing RT varied with age (p < 0.0001), region of residence (p < 0.0001), and year of diagnosis (p = 0.01). RT dose > or = 53.5 Gy varied with age (p < 0.0001), region of residence (p < 0.0001), and year of diagnosis (p = 0.0002). Median survival was 11 months among patients receiving RT and 3 months among those not receiving RT. The percentage of survival time spent in the hospital was similar among those who received from 49.5 to < 53.5 Gy, compared to > or = 53.5 Gy. Overall survival and the adjusted relative risk of death varied with age and region of residence.
Conclusion: We observed practice variation in the treatment of patients with GBM according to age, region of residence, and year of diagnosis. Survival did not increase during the study period. The variation in RT dose between those receiving from 49.5 to < 53.5 Gy compared to > or =53.5 Gy was not paralleled by variation in survival between regions where one or the other of the dose ranges predominated, nor was variation in dose ranges among the regions paralleled by variation in the proportion of survival time spent in the hospital.