CTNI-45. UPFRONT CHEMOTHERAPY AND SUBSEQUENT RESECTION UTILIZING NEOADJUVANT STRATEGY FOR OLIGODENDROGLIOMAS

Abstract Although both of functional preservation and higher extent of resection are required in glioma surgery, maximal resection with the risk of functional sequela is uniformly performed regardless of tumor pathology and treatment sensitivity in the current practice. Oligodendrogliomas are known to be associated with relatively favorable prognosis, however, many patients still eventually succumb to death due to tumors. Improvement in the long-term survival rate and functional preservation would be the next step to be achieved. In our hospital, patients with 1p/19q-codeleted glioma have been treated by upfront chemotherapy, if deemed in need of adjuvant treatment after initial resection, since 2006. If the initial resection was incomplete, the second surgery was intended following tumor volume decrease by chemotherapy (second-look resection, SLR). Intentional staged resection was performed in several cases for whom presence of 1p/19q codeletion was strongly suggested based on preoperative imaging characteristics. Utility of this strategy was evaluated. Forty-one patients with 1p/19q-codeleted glioma have been treated with the strategy. Of these, 30 were grade 2, and 11 were grade 3 tumors. In 9 of the 41 cases, radiotherapy was prescribed immediately after chemotherapy or SLR. Median tumor volume decrease rate by chemotherapy in the cases with initial incomplete resection was -35%. SLR following tumor volume decrease was performed in 22 cases. Median progression-free survival and overall survival after the initiation of chemotherapy were 81 months and 175 months for each in both of the total 41 cases and 32 cases for whom radiotherapy was deferred. Most of the recurrence occurred in the residual FLAIR high intensity. Upfront chemotherapy and subsequent resection strategy utilizing chemotherapeutic response provides more precise resection as well as reduction of resection volume as compared with one-time maximal safe resection. Radiotherapy may be indicated for the cases with residual FLAIR abnormality after chemotherapy or SLR.