ESTRO 2023 - Abstract Book

S905

Digital Posters

ESTRO 2023

Conclusion Re-RT using PT/CIRT is a feasible and safe treatment in case of recurrent or RT-induced meningiomas. PT/CIRT can improve dose conformity and reduce RT dose to OARs potentially leading to clinical benefits in terms of toxicity. Moreover, CIRT provides an increased relative biological effectiveness, which could be beneficial on LC considering RT-resistance of recurrent (mostly high grade) and RT-induced meningiomas. A longer follow-up and prospective clinical studies on a larger cohort of patients are necessary to evaluate the real role of PT/CIRT re-RT in this setting

PO-1132 CSI or whole brain irradiation combined with HSCT for CNS recurrence of hematopoietic tumors.

Y. Shimizu 1 , S. Nakamura 2 , H. Okamoto 2 , T. Nakaichi 2 , A. Aikawa 3 , J. Itami 4 , H. Igaki 3

1 Shin-Matsudo central general hospital, Radiation Therapy , Chiba, Japan; 2 National Cancer Center Hospital, Medical Physics, Tokyo, Japan; 3 National Cancer Center Hospital, Radiation Oncology, Tokyo, Japan; 4 Shin-Matsudo central general hospital, Radiation Therapy, Chiba, Japan Purpose or Objective In order to determine the index for selecting appropriate radiation coverage, we reviewed the progress of patients who underwent hematopoietic stem cell transplantation (HSCT) and craniospinal irradiation (CSI) or whole brain irradiation (WBI) for central nervous system (CNS) recurrence of hematopoietic tumors. Materials and Methods Time to relapse and overall survival were verified for 27 patients who underwent HSCT and WBI or CSI therapy for CNS recurrent of hematopoietic tumors, at a single institution between January 2007 and March 2022, Whole brain and whole spinal cord irradiation in 22 cases and whole brain irradiation in 5 cases. All patients underwent HSCT within 6 months before and after irradiation. Radiotherapy was 3DCRT in all patients. Dose fractionation was 12-40 Gy/6-20 fr. Twenty-six of the 27 patients underwent intrathecal chemotherapy. The 22 patients who received CSI had a median overall survival of 13 months and a recurrence-free survival of 11 months, and the sites of recurrence during the observation period were bone marrow in 6 patients, central nervous system in 4 patients, other in 2 patients, and no recurrence in 10 patients. In a part of CSI irradiated patients, recurrence-free survival of more than 10 years after irradiation was achieved. There was a patient in which the patient died two months after CSI, even though there was no lesion in the spinal cord but intracranial lesion. In the group that received WBI, one of the four patients who received WBI and intrathecal chemotherapy developed a recurrence in the dural space one month after irradiation and died within three months, and one patient died of CPA of unknown cause six months after irradiation without recurrence. The other had a recurrence-free survival at 12 years. The remaining patient developed multiple bone metastases 3 Results Median age 50 years (17-66), median observation period 7 months (0.9-139 months). Patients included 5 AML, 8 ALL/LBL, 5 DLBCL, 8 ATL, 1 ENKL.