Rosetta Genomics' Eti Meiri and her colleagues present in The Oncologist a second-generation assay to identify cancers of unknown primary origin. The researchers write that their first-generation assay was based on a quantitative real-time PCR approach that could identify 25 tumor types, and the new assay is a microRNA-based, custom microarray that can distinguish between 42 tumor types. They report in The Oncologist that the assay had 85 percent sensitivity and 88 percent concordance with clinicopathological assessments of 52 patients with CUP. "There is a growing need for an assay that can accurately identify the tumor-of-origin in CUP patients as there are an estimated 180,000 to 220,000 CUP cases per year in the US," said Rosetta Genomics CEO Kenneth Berlin in a statement. "In addition to presenting a diagnostic challenge, these cases also present a clinical challenge since knowing the tumor tissue-of-origin is crucial for selecting optimal treatment."