Prevalence and dynamics of clonal hematopoiesis caused by leukemia-associated mutations in elderly individuals without hematologic disorders.

Clonal hematopoiesis is frequently observed in elderly people. To investigate the prevalence and dynamics of genetic alterations among healthy elderly individuals, a cohort of 50 people >80 years was genotyped for commonly mutated leukemia-associated genes by targeted deep next-generation sequencing. A total of 16 somatic mutations were identified in 13/50 (26%) individuals. Mutations occurred at low variant allele frequencies (median 11.7%) and remained virtually stable over 3 years without development of hematologic malignancies in affected individuals. With DNMT3A mutations most frequently detected, another cohort of 160 healthy people spanning all age groups was sequenced specifically for DNMT3A revealing an overall mutation rate of 6.2% (13/210) and an age-dependent increase of mutation prevalence. A significant difference (p = 0.017) in the DNMT3A expression pattern was detected between younger and healthy elderly people as determined by qRT-PCR. To evaluate the selection of clonal hematopoietic stem cells (HSCs), bone marrow of two healthy individuals with mutant DNMT3A was transplanted in a humanized mouse model. Xenografts displayed stable kinetics of DNMT3A mutations over 8 months. These findings indicate that the appearance of low-level clones with leukemia-associated mutations is a common age-associated phenomenon, but insufficient to initiate clonal selection and expansion without the additional influence of other factors.

DNA index as a strong prognostic factor in patients with adenocarcinoma of the pancreatic head: results of a 5-year prospective study.

OBJECTIVES: To improve the devastating prognosis of pancreatic cancer; the identification of reliable predictive factors is crucial. The aim of the present study was to prospectively assess the prognostic value of DNA index determined by image cytometry as an predictive factor in pancreatic head cancer. METHODS: The DNA ploidy and the DNA index of 61 patients were evaluated by DNA image cytometry and were found to be correlated, as well as standard histopathologic parameters, with patient survival. RESULTS: Through the DNA image cytometry, 15 tumors (24.6%) were identified as diploid and 46 (75.6%) as nondiploid. The median DNA index in the entire cohort was 1.9 (range, 1.0-2.5). Tumor stage, lymph node status, lymph node index, lymphatic invasion, and DNA index were identified as prognostic factors in the univariate analysis, but only DNA index (hazard ratio, 3.137; 95% confidence interval, 1.149-8.566; P = 0.026) and lymph node status (hazard ratio, 0.377; 95% confidence interval, 0.186-0.765; P = 0.007) were identified as independent predictive factors in the multivariate analysis. CONCLUSIONS: The DNA index represents an independent predictive marker in patients with pancreatic head cancer and a potential tool in designing specific treatment strategies for patients with pancreatic cancer.