LMIC-19. A RETROSPECTIVE ANALYSIS OF PEDIATRIC RECURRENT PINEOBLASTOMA IN BEIJING

To explore the clinical characteristics of pediatric recurrent pineoblastoma in Beijing. Eighteen patients with newly diagnosed pineoblastoma were admitted to Beijing Shijitan Hospital between January 2014 and December 2022. The clinical data were retrospectively analyzed. Among the 18 patients (M/F=8:1), all were treated with surgery, and both radiotherapy and chemotherapy were administered. Nine patients experienced recurrence, and 2 patients died at last follow-up. The Median follow-up time were 56 months. The 5-year progression-free survival (PFS) and 5-year overall survival (OS) were (42.0±13.1) %, and (88.1±7.9) %, respectively. Among the 9 recurrent patients, one was < 3 years, and 8 cases ≥ 3 years. One girl and 8 boys relapsed; 7 cases were M0 and 2 with metastases at diagnosis; 7 cases were GTR; Two cases experienced recurrence within one year (10 months each), and one died. The other 7 patients relapsed after one year, the median time to first relapse were 24.0 (range: 10.0~49.0)months. The sex, age group, metastases at diagnosis, GTR or not, recurrent sites were not significantly affects PFS. Although the 9 recurrent patients received both cerebral and spinal irradiation and chemotherapy followed by surgery, the different order of chemotherapy or radiotherapy first were significantly affected the duration of remission. The median time before the first relapse after surgery was longer in those who treated under the order of craniospinal irradiation followed by chemotherapy than those of the inverse order (29m vs 13m, χ2=6.528, P=0.011). In addition, one case with germline mutation of Dicer1, experienced recurrences more than 3 times although received second surgery and second radiotherapy, and multiple cycles of chemotherapy in our center, which indicates poorer outcome. Pineoblastoma is rare and prone to relapse, the order of chemotherapy first may have shorter remission time before the first recurrence after surgery (P< 0.05).