Patterns of care and clinical outcome in assumed glioblastoma without tissue diagnosis: A population-based study of 131 consecutive patients.

Background: Elderly patients with glioblastoma and an accumulation of negative prognostic factors have an extremely short survival. There is no consensus on the clinical management of these patients and many may escape histologically verified diagnosis. The primary aim of this study was to characterize this particular subgroup of patients with radiological glioblastoma diagnosis without histological verification. The secondary aim was to evaluate if oncological therapy was of benefit.

Methods: Between November 2012 and June 2016, all consecutive patients presenting with a suspected glioblastoma in the western region of Sweden were registered in a population-based study. Of the 378 patients, 131 (35%) met the inclusion criteria of the present study by typical radiological features of glioblastoma without histological verification.

Results: The clinical characteristics of the 131 patients (72 men, 59 women) were: age ≥ 75 (n = 99, 76%), performance status according to Eastern Cooperative Oncology Group ≥ 2 (n = 93, 71%), significant comorbidity (n = 65, 50%) and multilobular tumors (n = 90, 69%). The overall median survival rate was 3.6 months. A subgroup of 44 patients (34%) received upfront treatment with temozolomide, with an overall radiological response rate of 34% and a median survival of 6.8 months, compared to 2.7 months for those receiving best supportive care only. Good performance status and temozolomide treatment were statistically significant favorable prognostic factors, while younger age was not.

Conclusion: Thirty-five percent of patients with a radiological diagnosis of glioblastoma in our region lacked histological diagnosis. Apart from high age and poor performance status, they had more severe comorbidities and extensive tumor spread. Even for this poor prognostic group upfront treatment with temozolomide was shown of benefit in a subgroup of patients. Our data illustrate the need of non-invasive diagnostic methods to guide optimal individualized therapy for patients considered too fragile for neurosurgical biopsy.