Mucoepidermoid carcinoma (MEC) is the most common carcinoma of the salivary glands. Here, we have used two large patient cohorts with MECs comprising 551 tumors to study clinical, histological, and molecular predictors of survival. One cohort (n = 167), with known CRCT1/3-MAML2 fusion status, was derived from the Hamburg Reference Centre (HRC; graded with the AFIP and Brandwein systems) and the other (n = 384) was derived from the population-based Cancer Registry of North Rhine-Westphalia (LKR-NRW; graded with the AFIP system). The reliability of both the AFIP and Brandwein grading systems was excellent (n = 155). The weighted kappa for inter-rater agreement was 0.81 (95% CI 0.65–0.97) and 0.83 (95% CI 0.71–0.96) for the AFIP and Brandwein systems, respectively. The 5-year relative survival was 79.7% (95% CI 73.2–86.2%). Although the Brandwein system resulted in a higher rate of G3-MECs, survival in G3-tumors (AFIP or Brandwein grading) was markedly worse than in G1/G2-tumors. Survival in > T2 tumors was markedly worse than in those with lower T-stage. Also, fusion-negative MECs had a worse 5-year progression-free survival. The frequency of fusion-positive MECs in the HRC cohort was 78.4%, of which the majority (86.7%) was G1/G2-tumors. In conclusion, the AFIP and Brandwein systems are useful in estimating prognosis and to guide therapy for G3-MECs. However, their significance regarding young age (≤ 30 years) and location-dependent heterogeneity of in particular G2-tumors is more questionable. We conclude that CRTC1/3-MAML2 testing is a useful adjunct to histologic scoring of MECs and for pinpointing tumors with poor prognosis with higher precision, thus avoiding overtreatment.

粘液表皮样癌（MEC）是最常见的唾液腺癌。在这里，我们使用了两个包含 551 个肿瘤的 MEC 的大型患者队列来研究生存的临床、组织学和分子预测因子。一组 (n = 167)，已知CRCT1/3-MAML2融合状态来自汉堡参考中心（HRC；用 AFIP 和 Brandwein 系统分级），另一个（n = 384）来自北莱茵-威斯特法伦州基于人群的癌症登记处（LKR-NRW；用 AFIP 和 Brandwein 系统分级） AFIP 系统）。AFIP 和 Brandwein 分级系统的可靠性都非常好（n = 155）。AFIP 和 Brandwein 系统的评分者间一致性加权 kappa 分别为 0.81（95% CI 0.65–0.97）和 0.83（95% CI 0.71–0.96）。5 年相对生存率为 79.7% (95% CI 73.2–86.2%)。尽管 Brandwein 系统导致 G3-MEC 的发生率更高，但 G3 肿瘤（AFIP 或 Brandwein 分级）的存活率明显低于 G1/G2 肿瘤。> T2 肿瘤的生存率明显低于 T 分期较低的肿瘤。还，融合阴性 MEC 的 5 年无进展生存期更差。HRC 队列中融合阳性 MEC 的频率为 78.4%，其中大多数 (86.7%) 是 G1/G2 肿瘤。总之，AFIP 和 Brandwein 系统可用于评估预后和指导 G3-MEC 的治疗。然而，它们对年轻（≤ 30 岁）和特定 G2 肿瘤的位置依赖性异质性的意义更值得怀疑。我们得出结论CRTC1/3-MAML2检测是 MEC 组织学评分的有用辅助手段，可用于以更高的精度查明预后不良的肿瘤，从而避免过度治疗。