Radiation induced tumors and secondary malignancies following radiotherapy

nema

GCT-36. TREATMENT RESULTS AND RADIATION-INDUCED TUMORS IN CASES OF CENTRAL NERVOUS SYSTEM GERM CELL TUMOR: A LONG-TERM FOLLOW-UP STUDY IN KUMAMOTO PREFECTURE

INTRODUCTION Central nervous system germ cell tumor (GCT) is one of the pediatric brain tumors. Although there have been epidemiological studies in the past, long-term prognosis and the late effects remained unclear. In this study, we examined GCT over the past 41 years in Kumamoto prefecture. METHODS Epidemiological features and complications with radiation-induced tumors were searched in patients diagnosed with GCT in the 41-year period from 1977 to 2018. RESULTS There were 93 patients diagnosed with GCT. These cases were divided into 14-year periods before and after incorporation of chemotherapy into the treatment, and the results for germinomas were compared. An improvement in the 10-year survival rate from 12 of 23 cases (52.2%) between 1977 and 1991 to 19 of 28 cases (67.9%) between 1992 and 2006 was observed. The 10-year survival rate for germinoma cases that received medical treatment during a more recent 5-year period between 2004 and 2009 increased to over 90%. However, 10.3% of all long-term survivors of GCT developed radiation-induced glioblastoma. The examination results showed that regardless of the tumor type, patients who received a high dose of radiation during their initial treatment developed the complication of radiation-induced glioblastoma within 10 to 25 years after their initial treatment. CONCLUSION This study suggests that the long-term survival rates for GCT are improving but the rate of radiation-induced glioblastoma in these cases are too high to be ignored. Long-term follow-up of at least 10 years is essential to effectively evaluate the details of treatment for pediatric brain tumors.

Establishment of Methylation-Specific PCR for the Mouse p53 Gene

Methylation-specific PCR (MSP) of the mouse p53 gene has not yet been reported. We searched the CpG islands, sequenced the bisulfited DNA, and designed PCR primers for methylation and unmethylation sites. DNA from a young mouse produced a strong PCR product with the unmethylated primer and a weaker band with the methylated primer. DNA from an old mouse produced bands of similar intensities with both primers. In radiation-induced tumors, DNA from an old mouse yielded similar bands with both types of primers. We suggest that MSP is a valuable technique for the epigenetic study of the mouse p53 gene.