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Combined surgical diagnostic tools improve gross total resection, not survival, in glioma
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Intraoperative MRI and 5-aminolevulinic acid were not predictors of improved survival in patients with glioma when used together, according to data from a Swiss study.
However, the use of both tools increases the likelihood of gross total resection during surgery, which may augment survival rates, results showed.
Previous studies have shown intraoperative MRI (iMRI) and 5-aminolevulinic acid (5-ALA) may improve survival individually in patients with glioma, according to study background. However, the two methods in combination had not been examined for survival effects.
Bawarjan Schatlo, MD, of the department of neurosurgery at Kantonsspital Aarau in Switzerland, and colleagues conducted a retrospective analysis comparing the effect of the combination of iMRI and 5-ALA with a control group of patients who underwent resection without iMRI.
Using multivariable regression analysis, the researchers evaluated 200 consecutive adult patients with high-grade glioma who were treated at a Swiss hospital between 2003 and 2011.
There were 55 patients in the combination arm and 145 patients in the control arm. All patients in the combination cohort had 5-ALA used during their surgery compared with 40% of the patients in the control group (P < .001).
Median OS was 13.8 months in the control group and 17.9 months in the iMRI group (P = .043); however, after adjusting for confounding variables, the difference was insignificant (HR = 1.23; 95% CI, 0.81-1.86).
Although 5-ALA enhanced the achievement of gross total resection (OR = 3.19; 95% CI, 1.28-7.93), it had no effect on OS or PFS after adjusting for resection status.
The use of iMRI seemed to be associated with improved OS (HR = 1.432; 95% CI, 1.012-2.027); however, the researchers suggested that was complicated by several variables.
“From a logical perspective as well as a statistical perspective, we believe that [gross total resection] is the variable that most likely confounds the relationship between iMRI and outcome,” Schatlo and colleagues wrote. “The main purpose of iMRI is to help the surgeon achieve [gross total resection] at surgery.”
When estimating OS without using gross total resection as a parameter, the effect of iMRI increased (HR = 1.36; 95% CI, 0.9-2.06), indicating that the greatest effect came from gross total resection rather than either or both of the combined methods.
The investigators noted the neuro-oncological management of high-grade glioma evolved over the course of the study and predictive biomarkers were not routinely assessed at the beginning of the study period. Additionally, all patients were pooled together instead of splitting them up by grades.
“Our study suggests that [gross total resection] … improves OS,” the researchers wrote. “In turn, the 5-ALA plus iMRI combination and neuronavigation enhance [gross total resection]. To determine which of these adjuncts has a higher impact on survival would require a complex study design with many groups and will remain elusive.” – by Anthony SanFilippo
Disclosure: The researchers report no relevant financial disclosures.
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