Impact of CRTC1/3-MAML2 fusions on histological classification and prognosis of mucoepidermoid carcinoma

Abstract

The aim of study was to evaluate the impact of CRTC1-MAML2 and CRTC3-MAML2 fusions on the histological classification of mucoepidermoid carcinoma (MEC) of the salivary glands and on the prognosis of patients. Methods and results: MEC cases (n=111) were screened for CRTC1-MAML2 and CRTC3-MAML2 fusions by reverse transcription polymerase chain reaction. We developed a system of 'molecular Armed Forces Institute of Pathology (AFIP) classification' that combined the AFIP histological classification proposed by Goode et al. and the presence of CRTC1-MAML2 or CRTC3-MAML2 fusions. MEC cases positive for CRTC1-MAML2 or CRTC3-MAML2 fusion formed a favourable tumour subset that was distinct from fusion-negative cases. When positive for the fusions, 'high-risk' patients, including those with a higher histological grade or an advanced clinical stage, showed an excellent prognosis. For overall survival, 'molecular AFIP classification' was selected as a powerful independent prognostic factor (P=0.0038), as was the clinical stage (P=0.0032). For disease-free survival, 'molecular AFIP classification' was also selected as an independent prognostic factor (P= 0.0006). Conclusions: Molecular AFIP classification may be useful in predicting the prognosis of patients with MEC. © 2011 Blackwell Publishing Limited.