Unfavorable prognosis of CRTC1‐MAML2 positive mucoepidermoid tumors with CDKN2A deletions

The CRTC1‐MAML2 fusion oncogene underlies the etiology of mucoepidermoid salivary gland carcinoma (MEC) where it confers a favorable survival outcome as compared with fusion‐negative MEC. While these analyses suggested that detection of CRTC1‐MAML2 serves as a useful prognostic biomarker, we recently identified outlier cases of fusion‐positive MEC associated with advanced‐staged lethal disease. To identify additional genetic alterations that might cooperate with CRTC1‐MAML2 to promote disease progression, we performed a pilot high‐resolution oligonucleotide array CGH (aCGH) and PCR‐based genotyping study on 23 MEC samples including 14 fusion‐positive samples for which we had clinical outcome information. Unbiased aCGH analysis identified inactivating deletions within CDKN2A as a candidate poor prognostic marker which was confirmed by PCR‐based analysis (CDKN2A deletions in 5/5 unfavorable fusion‐positive cases and 0/9 favorable fusion‐positive cases). We did not detect either activating EGFR mutations, nor copy number gains at the EGFR or ERBB2 loci as poor prognostic features for fusion‐positive MEC in any of the tumor specimens. Prospective studies with larger case series will be needed to confirm that combined CRTC1‐MAML2 and CDKN2A genotyping will optimally stage this disease. © 2009 Wiley‐Liss, Inc.