BT-5 LONG-TERM OUTCOME OF CLIVAL CHORDOMAS AT A SINGLE INSTITUTION

Abstract

Abstract Purpose Chordoma is a rare malignant tumor, about 30% of which occurs in the clivus. The purpose of this study is to investigate the outcome after treatment of clival chordoma in our institute. Methods Nineteen patients {M/F=11/8, mean age: 50.4 (15-72) years} who were treated between 1987 and 2021 and followed for at least 6 months were retrospectively evaluated for survival and local control rate. Results The cumulative survival rate was 89.2% at 5 years, 82.3% at 10 years, and 54.9% at 25 years, and the median OS was 107 (6-359) months. 4 deaths: 2 tumor deaths (1 from poorly differentiated chordoma), 2 non-tumor deaths (1 from IC rupture after heavy ion radiotherapy). The cumulative local control rate was 47.3% at 5 years and 35.5% at 10 years, with a median progression-free survival (PFS) of 41 (0-278) months. There was no difference in OS (p=0.85) or PFS (p=0.90) between the two groups, with 6 cases of gross total resection, GTR (all transsphenoidal) and 13 cases of non-GTR (9 transsphenoidal, 4 transcranial) at first surgery. In the 4 patients without irradiation (1 GTR, 3 non-GTR), no disease progression (PD) was observed, and the mean OS was 170 (69-278) months. Of the 15 patients irradiated, 6 were irradiated before PD and 9 were irradiated after PD, and there was no difference in OS or PFS between the two groups, i.e., the timing of irradiation. One patient with refractory chordoma was found to have elevated TMB levels by cancer genome testing and is currently receiving pembrolizumab, which has resulted in significant tumor shrinkage. Conclusion The patients with clival chordoma have a varied course, which may be due to differences in molecular biology. Cancer genome testing may provide new treatment options, such as molecularly targeted drugs and immune checkpoint inhibitors, for refractory cases.