CN-18 * RELATIONSHIPS BETWEEN DOSE INTENSITY, TOXICITY, AND OUTCOME IN OLIGODENDROGLIAL TUMORS (OG) TREATED WITH PCV REGIMEN

Abstract

BACKGROUND: In grade II and codeleted grade III gliomas, the procarbazine-CCNU-vincristine (PCV) combination increase survival when added to radiotherapy as first line treatment, despite the important toxicity of this treatment schedule. Our objective was to analyze the tolerance, feasibility and impact of dose intensity of the PCV regimen on outcome for patients with OG. METHODS: We retrospectively reviewed all grade III OG patients receiving PCV (CCNU:110mg/m2) who were referred to our two institutions. The total dose and dose adaptation, cycle delay, dose intensity, toxicity and premature discontinuation of CCNU were analyzed. Impact of these factors on patient outcome was evaluated. RESULTS: Between 2007 and 2011, 89 patients received PCV. Only 37% completed 6 cycles, whereas 13.4% prematurely discontinued PCV because of toxicity. Cycle delay and dose reduction were observed for 62% and 70% patients, respectively. Grade 3 and 4 toxicities were observed in 38% and 8% patients, respectively. Among patients who did not progress under PCV regimen, by multivariate analysis, premature discontinuation for toxicity was significantly correlated with poor PFS (p = 0.023, Hazard ratio (HR):2.354) and OS (p = 0.021, HR:5.093). By univariate analyses, absence of CCNU dose adaptation was correlated to poor PFS (p = 0.032). For OS, pejorative factors were high total CCNU dose (p = 0.029), absence of cycle delay (p = 0.009), absence of CCNU dose adaptation (p = 0.020) and grade 3/4 toxicities (p = 0.013). High CCNU dose-intensity tended to poorly impact PFS (p = 0.053) and OS (p = 0.112). By multivariate analysis, absence of CCNU dose adaptation remained significant for PFS (p = 0.001), while OS was negatively impacted by the absence of cycle delay (p = 0.049) and grade 3/4 toxicities (p = 0.045). CONCLUSION: Despite the efficacy of the PCV regimen, significant toxicity is associated with this schedule, which appears to impact its feasibility and efficacy. The optimal PCV schedule should be redefined taking into account this finding.