Prognosis for Glioblastoma Multiforme (GBM)
Glioblastoma multiforme has a poor prognosis with median survival of approximately 15 months with standard treatment, and only 3-5% of patients survive longer than 36 months. 1
Survival Statistics
The prognosis for GBM remains dismal despite advances in treatment:
- Median overall survival: 15 months with standard treatment 1, 2
- 2-year survival rate: 27% 1
- 5-year survival rate: 5-7.2% 3, 4
Survival varies significantly based on molecular markers:
- MGMT methylated: 23 months median survival, 49% 2-year survival 1
- MGMT unmethylated: 13 months median survival, 12% 2-year survival 1
Prognostic Factors
Several factors influence prognosis in GBM:
Favorable prognostic factors:
- Younger age (<50 years) 1
- Good performance status (KPS >70) 1, 5
- Maximal safe surgical resection 1, 6
- MGMT promoter methylation 1, 7
- IDH mutation (typically in secondary GBM) 3, 7
- 1p/19q co-deletion (in oligodendroglial components) 1, 3
Unfavorable prognostic factors:
- Advanced age (>65 years) 1
- Poor performance status 1
- Unmethylated MGMT promoter 1
- Wild-type IDH 1, 3
- Rapid tumor growth (doubling time of approximately 50 days) 8
Treatment Impact on Survival
Standard treatment for newly diagnosed GBM includes:
- Maximal safe surgical resection
- Radiotherapy with concurrent temozolomide
- Adjuvant temozolomide
This approach provides a 2.5-month survival benefit compared to radiotherapy alone, with median survival increasing from 12.1 to 14.6 months 5.
For elderly patients (>65-70 years), treatment considerations differ:
- Hypofractionated radiotherapy (40 Gy in 15 fractions) is preferred over standard radiotherapy (60 Gy in 30 fractions) 1
- For MGMT methylated tumors: Temozolomide alone may be appropriate 1
- For MGMT unmethylated tumors: Radiotherapy alone is recommended 1
- Combined short-course radiotherapy with temozolomide shows median survival of 7.5-12.4 months in patients >70 years 1
Disease Progression and Recurrence
GBM grows extremely rapidly with:
- Estimated growth rate of 1.4% per day 8
- Radiographic volume-doubling time of approximately 50 days 8
- Nearly universal recurrence despite treatment 2
At recurrence, options include:
- Re-operation (when feasible)
- Bevacizumab (provides progression-free survival benefit but limited overall survival impact) 1
- Clinical trials
- Palliative care
Long-term Survivors
Long-term survival (>36 months) is rare but associated with:
- MGMT promoter methylation (present in all documented long-term survivors in one study) 7
- IDH1 mutation (particularly in GBM with oligodendroglial components) 7
- Gross total resection followed by chemoradiotherapy 7
Conclusion
Despite aggressive multimodal therapy, GBM remains one of the most lethal malignancies with extremely poor long-term outcomes. Molecular markers, particularly MGMT methylation status and IDH mutation, provide important prognostic information and may guide treatment decisions, especially in elderly patients.