title: Can the prognosis of individual patients with glioblastoma be predicted using an online calculator?
abstract: BACKGROUND
  In an exploratory subanalysis of the European Organisation for Research and Treatment of Cancer and National Cancer Institute of Canada (EORTC/NCIC) trial data, Gorlia et al. identified a variety of factors that were predictive of overall survival, including therapy administered, age, extent of surgery, mini-mental score, administration of corticosteroids, World Health Organization (WHO) performance status, and O-methylguanine-DNA methyltransferase (MGMT) promoter methylation status. Gorlia et al. developed 3 nomograms, each intended to predict the survival times of patients with newly diagnosed glioblastoma on the basis of individual-specific combinations of prognostic factors. These are available online as a "GBM Calculator" and are intended for use in patient counseling. This study is an external validation of this calculator.
  
  
  METHODS
  One hundred eighty-seven patients from 2 UK neurosurgical units who had histologically confirmed glioblastoma (WHO grade IV) had their information at diagnosis entered into the GBM calculator. A record was made of the actual and predicted median survival time for each patient. Statistical analysis was performed to assess the accuracy, precision, correlation, and discrimination of the calculator.
  
  
  RESULTS
  The calculator gives both inaccurate and imprecise predictions. Only 23% of predictions were within 25% of the actual survival, and the percentage bias is 140% in our series. The coefficient of variance is 76%, where a smaller percentage would indicate greater precision. There is only a weak positive correlation between the predicted and actual survival among patients (R(2) of 0.07). Discrimination is inadequate as measured by a C-index of 0.62.
  
  
  CONCLUSIONS
  The authors would not recommend the use of this tool in patient counseling. If departments were considering its use, we would advise that a similar validating exercise be undertaken.
authors.affiliation: Department of Neurosurgery, Salford Royal NHS Foundation Trust, Stott Lane, Salford, United Kingdom. cjcparks@gmail.com
authors.forename: Christopher
authors.initials: C
authors.lastname: Parks
authors.forename: James
authors.initials: J
authors.lastname: Heald
authors.forename: Gregory
authors.initials: G
authors.lastname: Hall
authors.forename: Ian
authors.initials: I
authors.lastname: Kamaly-Asl
mesh_terms: D001932:Brain Neoplasms / Q000401:mortality* / Q000628:therapy; D003131:Combined Modality Therapy; D003627:Data Interpretation, Statistical; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D005909:Glioblastoma / Q000401:mortality* / Q000628:therapy; D006801:Humans; D020407:Internet; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D049451:Nomograms; D011379:Prognosis; D012189:Retrospective Studies; D018570:Risk Assessment; D015996:Survival Rate
keywords: GBM calculator; glioblastoma, prognosis prediction
references.citation: Lancet Oncol. 2008 Jan;9(1):29-38
references.pmid: 18082451
references.citation: Br J Radiol. 2012 Sep;85(1017):e729-33
references.pmid: 22215883
references.citation: Neuro Oncol. 2010 Jul;12(7):725-35
references.pmid: 20364023
references.citation: Ann Intern Med. 2001 Jun 19;134(12):1096-105
references.pmid: 11412049
references.citation: J Neurooncol. 2011 Nov;105(2):325-35
references.pmid: 21523485
references.citation: Neuro Oncol. 2008 Feb;10(1):79-87
references.pmid: 17993634
references.citation: BMJ. 2009 May 28;338:b605
references.pmid: 19477892
references.citation: N Engl J Med. 2005 Mar 10;352(10):987-96
references.pmid: 15758009
references.citation: J Clin Oncol. 2005 Feb 20;23(6):1278-88
references.pmid: 15718326
references.citation: Int J Palliat Nurs. 2008 Jul;14(7):316, 318-25
references.pmid: 18959280
references.citation: J Rheumatol. 2010 Nov;37(11):2216-20
references.pmid: 20843902
references.citation: Semin Oncol. 2003 Dec;30(6 Suppl 19):10-4
references.pmid: 14765378
references.citation: Neuro Oncol. 1999 Jan;1(1):14-25
references.pmid: 11554386
references.citation: Acta Neurochir (Wien). 2011 Jun;153(6):1211-8
references.pmid: 21479583
references.citation: J Neurooncol. 2011 Aug;104(1):351-6
references.pmid: 21221714