title: Does stereotactic eligibility for the treatment of glioblastoma cause selection bias in randomized studies?
abstract: The purpose of this study was to evaluate the potential selection bias using stereotactic eligibility as a criteria for participation in studies of glioblastoma multiforme. Radiation Therapy Oncology Group (RTOG) 90-06 comparing 60 Gy in 30 fractions with BCNU and 72 Gy in 60 fractions with BCNU was analyzed based on eligibility criteria used to enter patients on RTOG 93-05 using a stereotactic boost for patients with glioblastoma. Five hundred nine patients with histopathologically confirmed glioblastoma multiforme were analyzed; of these, 137 met criteria for 93-05 and 372 did not. Recursive partitioning analysis (RPA) was used to evaluate for differences. The RPA distribution in stereotactic radiosurgery (SRS)-eligible and -ineligible patients was similar. The median survival for RPA class 3 SRS-eligible patients was 1.4 years and -ineligible patients 1.4 years. For RPA class 4, the median survival was 1.0 years for eligible patients and 0.9 years for ineligible patients (P = 0.0421). For class 5 patients, the median survival was 8.3 months versus 7.2 months (P = 0.09). RPA class 6 patients had a median survival of 1.7 months versus 2.7 months for ineligible patients (P = 0.199). By analyzing previously randomized patients in a study not using a stereotactic boost, there does not appear to be a survival benefit for those patients who fit the criteria for consideration of a stereotactic boost in patients with glioblastoma multiforme.
authors.affiliation: Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA, USA. lustig@xrt.upenn.edu
authors.forename: Robert A
authors.initials: RA
authors.lastname: Lustig
authors.forename: Charles B
authors.initials: CB
authors.lastname: Scott
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Curran
mesh_terms: D000328:Adult; D000368:Aged; D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use; D002330:Carmustine / Q000627:therapeutic use; D016543:Central Nervous System Neoplasms / Q000145:classification / Q000188:drug therapy / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D005260:Female; D005909:Glioblastoma / Q000145:classification / Q000188:drug therapy / Q000532:radiotherapy* / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011379:Prognosis; D016634:Radiosurgery; D016032:Randomized Controlled Trials as Topic; D015983:Selection Bias; D016019:Survival Analysis
chemical_list: D018906:Antineoplastic Agents, Alkylating; D002330:Carmustine