Possibility of molecular targeting therapy for the treatment of cancer of unknown primary origin by analysis of intracellular signaling molecules.

Recently, antibody-mediated epidermal growth factor receptor (EGFR) blockade has become a major research focus, and a number of clinical studies on this new treatment have been started in the field of clinical oncology. This retrospective study investigated the role of KRAS gene mutations and clinical features for possibilities for new therapies in patients with cancer of unknown primary (CUP). We investigated the role of KRAS, PIK3CA and BRAF gene mutations and clinical features for possibilities for new therapies in patients with CUP. Nine patients with metastases from an unknown primary tumor were included in this retrospective study. The KRAS, BRAF and PI3KCA mutational analyses were carried out by means of PCR using genomic DNA for each PCR reaction. The mutation rate in CUP for codon 12 or 13 of the KRAS gene and for PIK3CA was lower than that in colorectal cancer, while the same mutation rate for BRAF was almost the same in the two; this means that the EGFR antibodies can possibly treat CUP.