In the Journal of Molecular Diagnostics, the Technical University of Munich's Stefanie Avril and her colleagues report that there is intratumor heterogeneity in microRNA expression in breast cancer. The researchers examined 132 tumor samples, including metastases, from 16 patients for expression of miR-31, miR-335, miR-10b, and miR-210 as well as for four control genes. They found that miRNA expression varied within primary tumors and within metastases. "We found considerable intratumoral heterogeneity in miRNA expression with a mean CV of 40% (30% to 51%) within primary breast cancers and 40% (26% to 55%) within different lymph node metastases from the same patient. These findings were consistent for all four miRNAs studied," the researchers write. They add that "reliable assessment of breast cancer miRNA profiles should include sampling of the primary tumor in several locations, or sampling of several tumor-involved lymph nodes when deriving miRNA expression profiles from metastases."

Also in the Journal of Molecular Diagnostics, researchers at Eli Lilly describe their work on detecting cell-free DNA, which they say may serve as a cancer treatment biomarker and may be used to determine genetic alterations in tumors. The researchers looked at tumor and plasma samples from 20 patients with advanced cancer, as well as 16 controls, for variants in the TP53 gene and to determine the methylation status of CpG islands in various promoters of disease-related genes. They were able to detect a TP53 gene mutation in the plasma samples from of two patients that they then confirmed was in those patients' tumor samples. "The findings suggest that in cases of advanced disease, measurable quantity of cfDNA is present in cell-free plasma, cfDNA can be quantified, and cfDNA is of adequate quality to allow genetic variation analysis and determine sequence-specific DNA methylation status," they add.