Effect Of Leucovorin On Radiation-Induced Brain Injury And Tumor Radiosensitivity In Patients Of Npc: A Retrospective Analysis.

e18552 Background: Nasopharyngeal carcinoma (NPC) is a typical type of head and neck cancers with its high prevalence areas in Southeast of China. On account of the prolongation of life, the severe complications developed such as radiation encephalopathy (REP). Currently many methods are used to cure REP but the outcomes are limited, such as corticosteroids, hyperbaric oxygen, antiplatelet agents and so on. The aim of this study is 1) to evaluate the protective effect of Calcium leucovorin (LV), a reduced folic acid, on REP in NPC patients. 2) to investigate the progression-free survival (PFS) and overall survival (OS) in NPC treated with or without LV. Methods: We conducted a retrospective, observational cohort study using de-identified, curated data in the Fifth Affiliated Hospital of SYSU included 1075 patients diagnosed as NPC of Stage II, III, or IVa who had been treated from December 2002, through February 2014. The Leucovorin-Group (LV-Group) of 163 NPC patients were matching the preceding criteria and agreed to receive PFL chemotherapy (cisplatin 80 mg/m², 5-fluorouracil 1000 mg/m²/d, and leucovorin 120 mg/m²) every 3 weeks. The Non-leucovorin-Group (NLV-Group) of 913 patients with similar disease status who did not receive leucovorin during the same period. Histologically there were 260 patients of PF chemotherapy (PF-Group) and 653 patients of other regimen chemotherapy (NPF-Group) in NLV-Group. REP were evaluated according to MRI and CT scan imaging studies. Time to progress (TTP), the real-world local control rate (rwLCR) and OS were compared across the two cohorts using the log-rank test. REP were compared using Chi-Square and Fisher’s Exact Test. Results: The TTP of the LV-Group as compared to the NLV-Group at 3, 5, 8, 10,12 and 16 years were 98.96% vs 94.97%, 95.57% vs 90.08%, 92.01% vs 85.22%, 90.67% vs 84.39%, 88.59% vs 84.26% and 88.54% vs 81.06%, respectively. The incident of REP in LV-Group is lower than that of the NLV-Group significantly( P= 0.0413). The OS of LV-Group as compared to PF-Group at 3, 5,10 and 12 years were 97.42% vs. 91.24%, 94.61% vs. 87.44%, 88.74% vs. 81.98%和88.74% vs. 78.57%, respectively. The OS of LV-Group got higher than that of PF-Group ( P= 0.0269). The OS of LV-Group was significantly higher than that of PF-Group with 90.83% vs. 82.12% in stage I-III(P = 0.0348). The rwLCR of LV-Group as compared to PF Group were 97.06% vs. 73.91% in stage T4 ( P= 0.0133). Conclusions: Leucovorin can significantly reduce the incidence of REP of NPC combined with PF regiment. It may improve the tumor radiosensitivity in NPC patients.