miRNA-ISH for Cancer of Unknown Primary
World-wide approximately 5% of all cancers are determined to have an occult or unknown primary location, upon initial assessment, prior to completing a full pathology report. [Oien] Unfortunately in 20-50% of CUP cases the primary tumor is never found. These cancers of unknown primary (CUP) result from metastasis. Occult cancer is most frequent in individuals around 60 years of age and an estimated 31,480 cases of CUP will be diagnosed in the US in 2019, making up around 2% of all US cancers. [Siegel] People with a family history of lung, kidney, or colorectal cancer are more likely than average to develop occult cancer. [Hemminki] Median survival time is 8-12 months, 80% of patients live only 6 months after diagnosis. [Losa]
Patients with metastatic cancer are often recruited to clinical trials using investigational drugs due to a lack of effective market approved treatment options. CUPs are most often found in the liver, lung, bone, brain; lymph nodes; and peritoneal and pleural serous cavities. [Oien] Once a tumor has been discovered, in order to provide a working diagnosis for the treating oncologist, a detailed pathology report must be prepared. A crucial component of this report is a microRNA in situ hybridization (miRNA-ISH) based classification of the tumor to aide categorization and for determining the site of origin.