Prognostic significance of molecular subgroups in survival outcome for children with medulloblastoma in Malaysia.

Introduction: Advancements in genomic profiling led to the discovery of four major molecular subgroups in medulloblastoma (MB), which have now been incorporated into the World Health Organization classification of central nervous system tumors. The current study aimed to determine the prognostic significance of the MB molecular subgroups among children in Malaysia. Methods: We assembled MB samples from children <18 years between January 2003 and June 2017 from four pediatric oncology centers in Malaysia. MB was sub-grouped using 850k DNA methylation testing at German Cancer Research Centre, Heidelberg, Germany. Results: Fifty samples from patients diagnosed and treated as MB were identified. Two (4%) of the 50 patients' tumor DNA samples were insufficient for analysis. Of the remaining 48 patients, 41 (85%) samples were confirmed as MB, while for 7 (15%) patients, DNA methylation classification results were discrepant with the histopathological diagnosis of MB, with various other diagnoses. Of the 41 MB patients, 15 patients were stratified as standard-risk (SR), 16 patients as high-risk (HR), and ten as infants (age <3 years old). Molecular subgrouping of the whole cohort revealed four (14%) WNT, 11 (27%) SHH, 10 (24%) Group 3, and 16 (39%) Group 4. Treatment abandonment rates for older children and infants were 22.5% and 10%, respectively. After censoring treatment abandonment, for SR patients, the 5-year event-free survival (EFS) and overall survival (OS) were 43.1% ± 14.7% and 46.9 ± 15.6%, respectively, while in HR, 5-year EFS and OS were both 63.6% ± 14.5%. Infants had a 5-year EFS and OS of 55.6% ± 16.6% and 66.7% ± 15.7%, respectively. WNT tumors had the best 5y-OS, followed by Group 3, Group 4, and SHH in children ≥3 years old. In younger children, SHH MB patients showed favorable outcomes. Conclusion: The study highlights the importance of DNA methylation profiling for diagnostic accuracy. Most infants had SHH MB, and their EFS and OS were comparable to those reported in high-income countries. Due to the relatively small cohort and the high treatment abandonment rate, definite conclusions cannot be made regarding the prognostic significance of molecular subgroups of MB. Implementing this high-technology investigation would assist pathologists in improving the diagnosis and provide molecular subgrouping of MB, permitting subgroup-specific therapies.

The BRCA1 and BRCA2 Genes in Early-Onset Breast Cancer Patients.

Approximately 5-10% of breast cancers are attributable to genetic susceptibility. Mutations in the BRCA1 and BRCA2 genes are the best known genetic factors to date. The goal of this study was to determine the structure and distribution of haplotypes of the BRCA1 and BRCA2 genes in early-onset breast cancer patients. We enrolled 70 patients diagnosed with early-onset breast cancer. A total of 21 SNPs (11 on BRCA1 and 10 on BRCA2) and 1 dinucleotide deletion on BRCA1 were genotyped using nested allele-specific PCR methods. Linkage disequilibrium (LD) analysis was conducted, and haplotypes were deduced from the genotype data. Two tightly linked LD blocks were observed on each of the BRCA1 and BRCA2 genes. Variant-free haplotypes (TAT-AG for BRCA1 and ATA-AAT for BRCA2) were observed at a frequency of more than 50% on each gene along with variable frequencies of derived haplotypes. The variant 3'-subhaplotype CGC displayed strong LD with 5'-subhaplotypes GA, AA, and GG on BRCA1 gene. Haplotypes ATA-AGT, ATC-AAT, and ATA-AAC were the variant haplotypes frequent on BRCA2 gene. Although the clinical significance of these derived haplotypes has not yet been established, it is expected that some of these haplotypes, especially the less frequent subhaplotypes, eventually will be shown to be indicative of a predisposition to early-onset breast cancer.

Pilot study of the sensitivity and specificity of the DNA integrity assay for stool-based detection of colorectal cancer in Malaysian patients.

BACKGROUND: To assess the diagnostic potential of tumor-associated high molecular weight DNA in stool samples of 32 colorectal cancer (CRC) patients compared to 32 healthy Malaysian volunteers by means of polymerase chain reaction (PCR). METHODS: Stool DNA was isolated and tumor-associated high molecular weight DNA (1.476 kb fragment including exons 6-9 of the p53 gene) was amplified using PCR and visualized on ethidium bromide-stained agarose gels. RESULTS: Out of 32 CRC patients, 18 were positive for the presence of high molecular weight DNA as compared to none of the healthy individuals, resulting in an overall sensitivity of 56.3% with 100% specificity. Out of 32 patients, 23 had tumor on the left side and 9 on the right side, 16 and 2 being respectively positive. This showed that high molecular weight DNA was significantly (p=0.022) more detectable in patients with left side tumor (69.6% vs 22.2%). Out of 32 patients, 22 had tumors larger than 1.0 cm, 18 of these (81.8%) being positive for long DNA as compared to not a single patient with tumor size smaller than 1.0 cm (p<0.001). CONCLUSION: We detected CRC-related high molecular weight p53 DNA in stool samples of CRC patients with an overall sensitivity of 56.3% with 100% specificity, with a strong tumor size dependence.