The aim of this study was to determine the genotoxicity of a locally produced nanocomposite by Universiti Sains Malaysia, Malaysia using Comet assay. Stem cells from human exfoliated deciduous teeth (SHED) were treated with the nanocomposite at five different concentrations (0.006, 0.0125, 0.025, 0.05, and 0.1 mg/ml) along with concurrent negative (medium alone) and positive control (zinc sulfate heptahydrate) and incubated at 37°C for 24 hours in an incubator at 5% CO2. The tail moment was used to assess the extent of DNA damage. The tail moment for the group of SHED treated with nanocomposite (for all the five different concentrations) was not statistically significant as compared to the negative control, suggesting that the locally produced dental nanocomposite did not induce any DNA damage. Hence, it can be concluded that the locally produced nanocomposite is non-genotoxic on stem cells from human exfoliated deciduous teeth.

INTRODUCTION: This study aimed to investigate the clinicopathological patterns and survival outcomes of patients with young-onset colorectal cancer (CRC) in Malaysia. METHODS: A total of 206 patients with young-onset CRC (age < 50 years at diagnosis) and 1,715 patients with late-onset CRC (age ≥ 50 years at diagnosis) diagnosed during 2002-2016 were included. The clinicopathological characteristics of patients with young-onset CRC were compared with those of patients with late-onset CRC during 2009-2013. Kaplan-Meier survival analysis was performed to determine the overall survival (OS) and disease-specific survival (DSS) in these patients. RESULTS: The overall proportion of young-onset CRC was 10.7%. The mean age for young-onset CRC was 39.5 ± 7.4 years, with a male-to-female ratio of 1.2:1. There were more Malay patients with young-onset CRC than late-onset CRC (44.0% vs. 19.9%, p = 0.004). Most CRCs were diagnosed at an advanced stage in both groups. However, young-onset CRC showed more aggressive tumour characteristics, such as poorer differentiation and mucinous subtype. Despite such differences, the OS and DSS in both groups were similar (five-year OS for young-onset CRC vs. late-onset CRC: 44.2% vs. 49.0%, p = 0.40; five-year DSS for young-onset CRC vs. late-onset CRC: 48.8% vs. 57.6%, p = 0.53; mean survival of young-onset CRC vs. late-onset CRC: 4.9 years vs. 5.4 years, p = 0.15). Advanced stage at diagnosis and the treatment modality used were independent prognostic factors. CONCLUSION The unique ethnic and histological differences between patients with young- and late-onset CRC suggest that young-onset CRC may represent a distinct entity. However, despite such differences, both groups were equivalent.