Clinical feasibility of modified procarbazine and lomustine chemotherapy without vincristine as a salvage treatment for recurrent adult glioma

Procarbazine, lomustine and vincristine (PCV) chemotherapy is considered a salvage option for adult glioma; however, its significant toxicities frequently lead to dose reduction or discontinuation in patients with recurrent glioma. The current study evaluated the safety and efficacy of modified procarbazine and lomustine (PC) chemotherapy that omits vincristine and reduces the lomustine dose compared with those of conventional PCV chemotherapy. Using electronic medical records, all patients with adult recurrent glioma who received PC or PCV chemotherapy between 2009 and 2020 at Seoul St. Mary's Hospital or St. Vincent's Hospital were examined retrospectively. A total of 59 patients met the eligibility criteria. Among them, 15 patients received modified PC chemotherapy (PC group) and 44 patients received PCV chemotherapy (PCV group). The PC group presented a significantly lower hematology toxicity (anemia, 6.7 vs. 45.5%, P=0.02; thrombocytopenia 20.0 vs. 70.4%, P<0.001). Additionally, the clinical impacts of PC chemotherapy, including delay of a cycle, dose reduction, discontinuation of drug(s) or total cessation of chemotherapy, were significantly less frequent compared with the PCV group (26.7 vs. 68.2%, P=0.012). The overall survival of the PC group was also significantly longer than that of PCV group (396 vs. 232 days, P=0.042), while there was no significant difference in progression-free survival between the two groups (284.5 vs. 131 days, P=0.077). The results suggested that modified PC chemotherapy may be an alternative chemotherapeutic regimen with tolerable toxicity and without loss of clinical efficacy in patients with recurrent adult glioma. Further prospective and larger studies are required to validate our findings.