Relationships Between Dose Intensity, Toxicity, and Outcome in Patients with Oligodendroglial Tumors Treated with the PCV Regimen.

ABSTRACT

BACKGROUND/AIM: The drug combination of procarbazine, lomustine (CCNU) and vincristine (PCV) has been associated with efficacy in oligodendroglial gliomas (OG) when added to radiotherapy as the first line of treatment, despite the important toxicity of this treatment schedule. The aim of the present study was to analyze the tolerance, feasibility and impact of the dose intensity of the PCV regimen on outcome for patients with OG. PATIENTS AND METHODS: We retrospectively reviewed all patients with OG receiving PCV (CCNU=110 mg/m(2)) who were referred to our two Institutions. The total dose and dose adaptation, cycle delay, dose intensity, toxicity and discontinuation of CCNU were analyzed. Impacts on the outcome were evaluated. RESULTS: Between 2007 and 2011, 89 patients received PCV. PCV was administered at relapse in 73% of patients. Only 37% completed six cycles, 13.4% discontinued PCV because of toxicity, the other patients discontinued due to tumor progression. 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 whose disease did not progress under the PCV regimen, discontinuation due to toxicity was significantly correlated to poor progression-free survival (PFS p=0.023, hazard ratio=2.354) and poor overall survival (OS p=0.021, hazard ratio=5.093). A factor that negatively impacted PFS was the absence of CCNU dose adaptation (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 with the appropriate CCNU dose-intensity adaptation should be redefined taking into account this finding.