Survival and treatment patterns of glioblastoma in the elderly: a population-based study

Background: As the older segment of the population grows faster than any other age group, the number of elderly diagnosed with glioblastoma is expected to increase. The aim of this study was to explore survival and the treatment provided to elderly patients diagnosed with glioblastoma in a population-based setting. We further studied whether increased treatment aggressiveness may have contributed to a clinically important survival benefit in the elderly population.

Methods: From the Norwegian Cancer Registry, we included 2882 patients who were diagnosed with glioblastoma between 1988 and 2008.

Results: The proportion of patients ≥66 years was 42.5% (n = 1224), and 15.9% of patients (n = 459) were ≥75 years at diagnosis. Treatment patterns varied significantly between age groups (P < 0.001). Elderly patients (66 years) were less likely to receive multimodal treatment with resection combined with radiotherapy and/or chemotherapy. Elderly patients were more likely to receive a diagnosis of glioblastoma without histopathologic verification (P < 0.001). Among patients receiving multimodal treatment with surgical resection, radiotherapy, and chemotherapy, shorter survival was seen in the elderly (P < 0.001). Belonging to the age group ≥75 years was the strongest predictor of decreased survival (P < 0.001), thus seemingly of higher prognostic impact than the patterns of care. Increasing age, no tumor resection, no radiotherapy, and no chemotherapy were identified as independent predictors of reduced survival. There was a statistically significant, albeit debatable, clinically relevant survival advantage for the oldest patients (≥75 years) diagnosed in the last 5 years of the study.

Conclusions: Advancing age remains a very strong and independent negative prognostic factor in glioblastoma. Although there has been an increase in the aggressiveness of treatment provided to elderly with glioblastoma, the gain for the oldest age group seems at best very modest. The prognosis of the oldest age group remains very poor, despite multimodal treatment.