CRTC1-MAML2 and CRTC3-MAML2 fusions have been associated with favorable clinicopathological features of mucoepidermoid carcinomas. However, the significance of the MAML2 gene split has not been fully clarified. In the present study, 95 mucoepidermoid carcinomas (paraffin-embedded materials) were analyzed for CRTC1-MAML2 and CRTC3-MAML2 fusions by RT-PCR and for the MAML2 gene split by FISH. Quantitative RT-PCR for the CRTC1-MAML2 transcript was performed in selected cases. MLL gene involvement, which has been reported in some leukemia cases, was examined by FISH in fusion partner-unknown cases. CRTC1-MAML2 and CRTC3-MAML2 fusions were detected in 37 and 6 cases, respectively. The MAML2 gene split was detected in 62 cases, which included all CRTC1/3-MAML2 fusion-positive cases. The level of CRTC1-MAML2 transcript expression was highly variable, and its clinicopathological impact was unclear. The MLL gene split was not detected. Mucoepidermoid carcinomas negative for CRTC1/3-MAML2 and positive for the MAML2 gene split (n = 19) showed favorable clinicopathological tumor features similar to those positive for CRTC1/3-MAML2 fusions. Compared with negative cases (n = 33), mucoepidermoid carcinomas positive for the MAML2 split (n = 62) were associated with lower patient age, a mild female predilection, a smaller tumor size, less frequent nodal metastasis, a lower clinical stage, a lower histological grade, and longer overall and disease-free survival. The MAML2 gene split emerged as an independent prognostic factor for both overall and disease-free survival in multivariate prognostic analysis. The presence of the MAML2 gene split defines a distinct mucoepidermoid carcinoma subset that is associated clinicopathologically with favorable tumor features. (Cancer Sci 2013; 104: 85-92) M ucoepidermoid carcinomas represent 5% of all salivary gland tumors and 20% of salivary malignancies.(1,2) A subset of these carcinomas has been associated with a recurring chromosomal translocation, t(11;19)(q21;p13), which generates a fusion protein composed of the N-terminal of cAMP response element-binding protein (CREB)-regulated transcription coactivator 1 (CRTC1), also called MECT1, TORC1 or WAMP1, and the C-terminal of mastermind-like gene 2 (MAML2).(3-6) Recent data suggest that CRTC1-MAML2 induced-activation of CREB is critical for cell transformation.(5,6) CTCR1-MAML2 fusion has been detected in 40-80% of primary salivary gland mucoepidermoid carcinomas, and we and other research groups have shown that the fusion gene is associated with a distinct tumor subset with an indolent clinical course. and in Nakayama et al. (12) we reveal that CRTC3-MAML2 fusion-positive mucoepidermoid carcinoma cases have an excellent prognosis. These findings suggest that both CRTC1-MAML2 and CRTC3-MAML2 fusions may be associated with mucoepidermoid carcinoma cases with favorable clinicopathological tumor features. (13) CRTC1/3-MAML2 fusions have been detected using an RT-PCR technique, assuming that exon 1 of CRTC1/3 genes is fused to exons 2-5 of th...

Molecular AFIP classification may be useful in predicting the prognosis of patients with MEC.

Mucoepidermoid carcinoma (MEC) is rare, but the most common primary malignancy of the salivary gland and not infrequent in young individuals. CRTC1/3‐MAML2 fusions are frequently detected in MEC and are useful as a diagnostic biomarker. However, there has been debate as to whether the fusions have prognostic significance. In this study, we retrospectively collected 153 salivary gland MEC cases from 11 tertiary hospitals in Japan. As inclusion criteria, the MEC patients in this study had curative surgery as the initial treatment, received no preoperative treatment, and had no distant metastasis at the time of the initial surgery. The MEC diagnosis was validated by a central pathology review by five expert salivary gland pathologists. The CRTC1/3‐MAML2 fusions were detected using FISH and RT‐PCR. In 153 MEC cases, 90 (58.8%) were positive for CRTC1/3‐MAML2 fusions. During the follow‐up period, 28 (18.3%) patients showed tumor recurrence and 12 (7.8%) patients died. The presence of the fusions was associated with favorable tumor features. Of note, none of the fusion‐positive patients died during the follow‐up period. Statistical analysis showed that the presence of the fusions was a prognostic indicator of a better overall survival in the total and advanced‐stage MEC cohorts, but not in the early‐stage MEC cohort. In conclusion, CRTC1/3‐MAML2 fusions are an excellent biomarker for favorable overall survival of patients with salivary gland MEC.

Aims: To investigate the histological diversity of salivary mucoepidermoid carcinoma (MEC), its clinicopathological features, and its associations with CRTC1/ 3-MAML2 fusions. Methods and results: Salivary MEC cases (n = 177) were examined for CRTC1/3-MAML2 fusions, histological variants were classified, and tumours were graded according to four different grading systems. Adverse histological features considered to be unusual in MEC were also investigated. Of the 177 MEC cases, 110 were positive for CRTC1/3-MAML2 fusions. The classical variant was the most frequent in the fusion-positive case group, the fusion-negative case group, and the total case group. The clear/oncocytic variant was the second most frequent in the fusion-positive and total case groups. Oncocytic, Warthin-like and spindle variants were seen

Background The National Comprehensive Cancer Network (NCCN) guidelines recommend considering postoperative radiotherapy (PORT) for completely resected T1/2N0M0 salivary mucoepidermoid carcinomas when they show tumor spillage, perineural invasion, or intermediate/high‐grade histology. CRTC1/3‐MAML2 fusions have been associated with a favorable clinical outcome. Methods Forty‐seven T1/2N0M0 mucoepidermoid carcinoma cases positive for CRTC1/3‐MAML2 fusions were completely resected and were not treated with PORT. Results Pathologically, none of the cases showed tumor spillage or perineural invasion. Cases with intermediate/high‐grade histology numbered 9 (19%) to 26 (55%) with the currently used 3 different grading systems. During the follow‐up (median 60 months), locoregional tumor recurrence occurred in 4 cases, which were treated with surgery alone. At the last follow‐up (median 60 months; 7‐160), all patients were alive with no evidence of disease. Conclusion An excellent prognosis may be achieved without PORT in T1/2N0M0 mucoepidermoid carcinoma patients positive for CRTC1/3‐MAML2 fusions when the tumors are completely resected without tumor spillage.

To investigate optimal treatment planning using proton beams for non-squamous cell carcinoma of the head and neck (NSCHN), the dose distributions of plans involving pencil beam scanning (PBS) with or without a patient-specific aperture system (PSAS), passive-scattering proton therapy (PSPT) and X-ray intensity-modulated radiotherapy (IMRT) were compared. As clinical results, toxicities of PBS with PSAS, including changes in quality of life, were reported. Between April 2014 and August 2016, a total of 30 patients were treated using PBS with PSAS. In 20 patients selected at random, the dose distributions of PBS with or without the PSAS, PSPT and IMRT plans were compared. Neutron exposure by proton therapy was calculated using a Monte Carlo simulation. Toxicities were scored according to CTCAE ver. 4.0. Patients completed EORTC quality of life survey forms (QLQ-C30 and QLQ-HN35) before and 0–12 months after proton therapy. The 95% conformity number of PBS with the PSAS plan was the best, and significant differences were detected among the four plans (P < 0.05, Bonferroni tests). Neutron generation by PSAS was ~1.1-fold higher, but was within an acceptable level. No grade 3 or higher acute dermatitis was observed. Pain, appetite loss and increased weight loss were more likely at the end of treatment, but recovered by the 3 month follow-up and returned to the pretreatment level at the 12 month follow-up. PBS with PSAS reduced the penumbra and improved dose conformity in the planning target volume. PBS with PSAS was tolerated well for NSCHN.

Aims Mucoepidermoid carcinoma (MEC) is one of the most common salivary gland carcinomas. Epidermal growth factor receptor (EGFR) signalling pathway gene mutations are important in predicting a patient’s prognosis, selecting molecularly targeted drugs and estimating the efficacy of a molecular therapy. However, their significance in MEC have been poorly clarified. CRTC1/3–MAML2 fusions are specific to MEC and may be associated with favourable characteristics in these patients. Methods and results We looked for CRTC1/3–MAML2 fusions and gene alterations in the EGFR, RAS family (KRAS, HRAS and NRAS), PIK3CA, BRAF and AKT1 in 101 MEC cases. We also examined mutations in TP53. CRTC1/3–MAML2 fusions were found in 62.4% of the cases. KRAS, HRAS and PIK3CA mutations were detected in 6.9%, 2.0% and 6.9%, respectively, but other EGFR pathway genes were not mutated. In total, gene mutations (RAS/PIK3CA) in the EGFR pathway were detected in 14.9% of the cases. TP53 mutations were found in 20.8%. CRTC1/3–MAML2 fusions were associated with a better prognosis and RAS/PIK3CA mutations a worse prognosis of the patients, respectively, and both were selected as independent prognostic factors for the overall survival of the patients. TP53 mutations had no prognostic impact. CRTC1/3–MAML2 fusion‐positive rates were inversely associated with the patients’ age and the fusions were found in 82% of patients aged < 30 years. Conclusions RAS/PIK3CA mutations were frequently detected, and may be a biomarker for a poorer prognosis in MEC patients. CTRC1/3–MAML2 fusions were positive in most of the young MEC patients.

Background Preoperative diagnosis of salivary gland tumors (SGTs) by fine‐needle aspiration (FNA) cytology is challenging. Next‐generation sequencing (NGS)‐based assays for somatic mutations have a great advantage in that a large number of genes can be analyzed simultaneously. Although NGS may have an enormous diagnostic potential in cytology, to our knowledge, the significance of NGS in SGT cytology remains to be clarified. Methods In this pilot study, we retrospectively examined 32 frozen SGT samples obtained at surgery (14 malignant and 18 benign). After the stored frozen tumor tissues were thawed, aspirate samples were obtained using 22‐gauge needles and subjected to smear tumor samples and to DNA extraction for an NGS assay employing the Illumina AmpliSeq Cancer Hotspot Panel v2. The results were correlated to preoperative cytological diagnosis. Results The preoperative diagnoses obtained by FNA cytology included 23 negative lesions (no malignancy in 6 and benign tumor in 17) and nine positive lesions (suspicious for malignancy in 4 and malignancy in five), providing a sensitivity and a specificity of 9/14 (64%) and 18/18 (100%), respectively. The NGS assay detected somatic mutations in 10/14 malignant and 1/18 benign SGT cases, providing a sensitivity and a specificity of 71% and 94%, respectively. Conclusion The NGS assay may be helpful for detecting the malignant potential in SGT cases and can be used as an ancillary test for SGT cytology.