Abstract # 2053 Evaluation of the Functional Diffusion Map (fDM) as an early Biomarker of TTP and OS in High Grade Glioma

Presenter: Hamstra, Daniel

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Changes in tumor crossed diameter product (CDP), mean change in ADC, and fDM determined three weeks into treatment were compared to standard radiographic response at 10 weeks. By receiver operator curve analysis the changes in fDM at 3 weeks were most closely associated with RR at 10 weeks. Patients with progressive disease (PD) by standard radiographic response exhibited a total volume of tumor with any change in diffusion (VT) of 5.7 +/-1.4% compared to those with stable or responsive disease (SD/PR) with a VT of 17.8 +/- 2.8% (p<0.001).

Based upon this analysis patients were stratified based upon their VT. Patients with LOW fDM (VT <6.57%)were classified as PD (n=14) at 3 weeks and had a shorter TTP when compared to those with HIGH fDM(VT => 6.57, SD/PR, n=20) (median TTP 4.3 months vs. 7.3 months, p<0.04, log-rank). Early fDM stratification also correlated with shorter OS in the PD group compared to those without fDM predicted progression (median survival 7.4 months vs. 18.4 months, p=0.008, log-rank).

In contrast, neither the change in CDP nor the mean change in diffusion at 3 weeks were predictive of TTP or OS (p>0.1 for each, log-rank). There were no significant differences in the distribution of known prognostic factors (age, KPS, pathologic grade, tumor location, and extent of surgical resection) between those identified by fDM as PD vs. SD/PR (p>0.1 for each).

A Cox proportional hazard model incorporating: age, pathologic grade, surgical resection, tumor location, and fDM found fDM as the only factor retaining prognostic significance on OS (p<0.02). Similarly, only pathologic grade (p<0.03) and fDM (p<0.05) retained predictive power on a multivariate analysis of TTP. In addition, when VT was analyzed as a continuous variable each continuous rise in VT was associated with decreasing hazard of death (p=0.05).

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fDM Percentages for Grade III/IV Gliomas:

fDM Stratification & Overall Survival:

fDM Stratification & Progression Free Survival:

Multivariate Analysis:

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