PC or PCV, that is the question: Primary anaplastic oligodendroglial tumors treated with procarbazine and CCNU with and without vincristine

Background: While procarbazine with 1-(2- chloroethyl)-3-cyclohexyl-1-nitrosourea (PC) added to vincristine (PCV) was proven beneficial in the treatment of co-deleted anaplastic oligodendroglioma (AO), the question of whether PC alone is sufficient is important, as vincristine adds toxicity with uncertain benefit. This retrospective study provides a comparison of PC and PCV. Patients and Methods: Patients diagnosed with AO treated at the M.D. Anderson Cancer Center from June 1, 1993 to October 13, 2009 were selected from the database and were eligible if diagnosed with a primary AO and treated with either PC or PCV at some point. Ninety-seven patients were treated with such chemotherapy before first progression. Results: Initial treatment included radiation and chemotherapy (81.4%) or chemotherapy alone (18.6%). Twenty-one patients (21.6%) received PC during primary treatment, while 76 patients (78.4%) received PCV. Eleven patients reported neurotoxicity in the PCV arm vs. none in the PC arm. Out of the 97 patients, 45 were alive at last contact, with a median followup of 9.9 years. The median overall survival was 6.5 years (95% confidence interval=4.8-16.7 years), while the median progression-free survival was 2.9 years (95% confidence interval=2.0-6.3 years); these differences were not significant (p=0.61 and p=0.28, respectively). Conclusion: Initial therapy with PC achieved comparable results to those of PCV with a median follow-up of 9.9 years. Neurotoxicity was more frequent with vincristine. Although selecting only for patients with AO, rather than those with mixed histology, increased the likelihood of selecting for patients with tumors with co-deletions, further studies with correlative co-deletion status are required.